U.S. patent application number 14/787855 was filed with the patent office on 2016-04-14 for process for the removal of metal or impurities from electric arc furnace dust.
This patent application is currently assigned to SAUDI BASIC INDUSTRIES CORPORATION. The applicant listed for this patent is SAUDI BASIC INDUSTRIES CORPORATION. Invention is credited to Fazal-ur-Rehmen M. AWAN.
Application Number | 20160102382 14/787855 |
Document ID | / |
Family ID | 51492375 |
Filed Date | 2016-04-14 |
United States Patent
Application |
20160102382 |
Kind Code |
A1 |
AWAN; Fazal-ur-Rehmen M. |
April 14, 2016 |
PROCESS FOR THE REMOVAL OF METAL OR IMPURITIES FROM ELECTRIC ARC
FURNACE DUST
Abstract
A method for preparing Electric Arc Furnace dust (EAFD) for
metal recovery, comprising: a) mixing the EAFD comprising zinc
oxide or lead oxide, or a mixture of both, with a liquid and a
binder to produce an EAFD mixture; b) producing a shaped EAFD
pellet; and c) drying the shaped EAFD pellet is disclosed. A method
for recovering zinc from Electric Arc Furnace dust (EAFD),
comprising: a) heating the EAFD comprising at least one metal
comprising zinc in an inert gas atmosphere at a temperature ranging
from 700.degree. C. to 1100.degree. C.; and b) evaporating the at
least one metal comprising zinc from the EAFD and collecting the at
least one metal is also disclosed. A method for recovering an
impurity from Electric Arc Furnace dust (EAFD), comprising: a)
heating the EAFD comprising an impurity in an inert gas atmosphere
at a temperature ranging from 700.degree. C. to 1100.degree. C.;
and b) evaporating the impurity from the EAFD and collecting the
impurity is also disclosed. A method for recovering iron oxide from
Electric Arc Furnace dust (EAFD), comprising: a) heating the EAFD
comprising iron oxide and at least one metal in an inert gas
atmosphere at a temperature ranging from 700.degree. C. to
1100.degree. C.; and b) separating the iron oxide by evaporating
the at least one metal from the EAFD and leaving the iron oxide as
a residue is also disclosed.
Inventors: |
AWAN; Fazal-ur-Rehmen M.;
(Jubail, SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAUDI BASIC INDUSTRIES CORPORATION |
Riyadh |
|
SA |
|
|
Assignee: |
SAUDI BASIC INDUSTRIES
CORPORATION
Riyadh
SA
|
Family ID: |
51492375 |
Appl. No.: |
14/787855 |
Filed: |
April 24, 2014 |
PCT Filed: |
April 24, 2014 |
PCT NO: |
PCT/IB14/01391 |
371 Date: |
October 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61816987 |
Apr 29, 2013 |
|
|
|
Current U.S.
Class: |
423/500 ;
423/620; 423/623; 75/590; 75/654; 75/693; 75/770 |
Current CPC
Class: |
C22B 7/02 20130101; C22B
7/001 20130101; C22B 19/30 20130101; C22B 26/10 20130101; C22B
19/34 20130101; C22B 19/20 20130101; C22B 1/2406 20130101; Y02P
10/20 20151101; Y02P 10/214 20151101; C22B 13/025 20130101 |
International
Class: |
C22B 1/24 20060101
C22B001/24; C22B 19/34 20060101 C22B019/34; C22B 26/10 20060101
C22B026/10; C22B 19/20 20060101 C22B019/20; C22B 13/02 20060101
C22B013/02 |
Claims
1. A method for preparing Electric Arc Furnace dust (EAFD) for
metal recovery, comprising: a) mixing the EAFD comprising zinc
oxide or lead oxide, or a mixture of both, with a liquid and a
binder to produce an EAFD mixture; b) producing a shaped EAFD
pellet; and c) drying the shaped EAFD pellet.
2. (canceled)
3. The method according to claim 1, wherein the metal oxide is zinc
oxide.
4. The method according to claim 1, wherein the metal oxide is lead
oxide.
5. The method according to claim 1, wherein the liquid is
water.
6. The method according to claim 1, wherein the liquid is present
in an amount from about 6.0 wt % to 12.0 wt %, based on the total
weight of the EAFD mixture.
7. (canceled)
8. (canceled)
9. The method according to claim 1, wherein the binder is present
in an amount from about 0.01 wt % to about 5.0 wt %, based on the
total weight of the EAFD mixture.
10-15. (canceled)
16. The method according to claim 1, wherein the average pellet
size is from about 7.0 to 18 mm.
17. A method for recovering zinc from Electric Arc Furnace dust
(EAFD), comprising: a) heating the EAFD comprising at least one
metal comprising zinc in an inert gas atmosphere at a temperature
ranging from 700.degree. C. to 1100.degree. C.; and b) evaporating
the at least one metal comprising zinc from the EAFD and collecting
the at least one metal.
18. The method according to claim 17, wherein the at least one
metal is zinc.
19-22. (canceled)
23. The method according to claim 17, wherein the method comprises
reoxidizing the zinc to form zinc oxide and collecting the zinc
oxide.
24. (canceled)
25. A method for recovering an impurity from Electric Arc Furnace
dust (EAFD), comprising: a) heating the EAFD comprising an impurity
in an inert gas atmosphere at a temperature ranging from
700.degree. C. to 1100.degree. C.; and b) evaporating the impurity
from the EAFD and collecting the impurity.
26. (canceled)
27. The method according to claim 25, wherein EAFD is in the form
of a pellet.
28. The method according to claim 25, wherein the impurity
comprises lead, chlorine, or sodium, or a mixture thereof.
29-36. (canceled)
37. The method according to claim 25, wherein the method comprises
reoxidizing the lead to form lead oxide and collecting the lead
oxide.
38. The method according to claim 25, wherein the average pellet
size is from about 7.0 to 18 mm.
39-45. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/816,987, filed on Apr. 29, 2013, which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] Electric Arc Furnace Dust (EAFD), in one aspect bag house
dust (BHD), constitutes one of the largest industrial waste
materials produced. Several approaches are used for the treatment
of the EAFD. Numerous alternatives of pyrometallurgical and
hydrometallurgical approaches have been examined for treatment of
the EAFD in the last few decades. Some commonly used and
commercially successful pyrometallurgical process include the Waelz
Kiln and similar advanced processes that involve the reduction of
EAFD with coke or coal, lime and silica in rotary kiln furnaces.
However, these processes are very energy intensive, resulting in
high treatment cost, which can make them unfavorable for
stand-alone, on-site treatment of dust at most steel mills.
Hydrometallurgical processing that involves acidic and/or caustic
leaching followed by precipitation of metals can be less expensive
and energy consumptive, but generates considerable environmentally
objectionable effluent and the yield is much lower than that of the
pyrometallurgical routes. Some hybrid-combining pyre-metallurgy and
hydro-metallurgy approaches and specific technologies, like
Integrated Ezinex.RTM., Enviroscience MetWool, Ausmelt, Enviroplas,
etc. were developed and trialed recently. However, the capital and
processing costs of these methods can be high.
[0003] Today, steel plants world-wide are concerned about the
handling, storage and safe disposal of their waste materials
including bag house dust (BHD), which is listed as a hazardous
material (KO61) by International environmental protection agencies
(IEPA). The problem encountered in the processing of BHD is one of
finding an economical method of separating the zinc from the
remainder of the dust, which consists mainly of iron, manganese,
nickel, silicon and smaller quantities of other elements.
Typically, BHD is a liability for steel makers. All the existing Zn
extraction processes including pyrometallurgical,
hydrometallurgical or hybrid processes are very expensive and the
cost to process BHD ranges from $50-$250 per ton. The cost of
production of Zn is also very high. Zn in BHD is present either in
the form of zinc oxide (ZnO) or zinc ferrite (ZnO.Fe.sub.2O.sub.3).
Removing zinc from a bimetallic compound, such as zinc ferrite
(ZnO.Fe.sub.2O.sub.3), is more difficult than removing zinc from a
mixture of zinc oxide and iron oxide, when zinc and iron are
present as discrete compounds.
[0004] The removal and recovery of Zn, Pb, and/or Cd, etc. (so
called "tramp" elements), from the impurities of, Cl, Na, and/or K,
introduced in steel making processes and collected as BHD, while
environmentally desirable, cannot be currently achieved by low cost
technologies. Thus, a scalable and cost-effective dust treatment
process and metal extraction from Electric Arc Furnace Dust is
desired.
SUMMARY
[0005] In accordance with the purpose(s) of the invention, as
embodied and broadly described herein, the invention, in one
aspect, relates to a method for recovering a metal oxide from
Electric Arc Furnace dust (EAFD), comprising: [0006] a) mixing the
EAFD comprising zinc oxide or lead oxide with a liquid and a binder
to produce an EAFD mixture; [0007] b) producing a shaped EAFD
pellet; and [0008] c) drying the shaped EAFD pellet.
[0009] The invention disclosed here in another aspect relates to a
method for recovering zinc from Electric Arc Furnace dust (EAFD),
comprising: [0010] a) heating the EAFD comprising at least one
metal comprising zinc in an inert gas atmosphere at a temperature
ranging from 700.degree. C. to 1100.degree. C.; and [0011] b)
evaporating the least one metal comprising zinc from the EAFD and
collecting the at least one metal.
[0012] The invention disclosed here in a further aspect relates to
a method for recovering an impurity from Electric Arc Furnace dust
(EAFD), comprising: [0013] a) heating the EAFD comprising an
impurity in an inert gas atmosphere at a temperature ranging from
700.degree. C. to 1100.degree. C.; and [0014] b) evaporating the
impurity from the EAFD and collecting the impurity.
[0015] The invention disclosed here in yet another aspect relates
to a method for recovering iron oxide from Electric Arc Furnace
dust (EAFD), comprising: [0016] a) heating the EAFD comprising iron
oxide and at least one metal in an inert gas atmosphere at a
temperature ranging from 700.degree. C. to 1100.degree. C.; [0017]
b) separating the iron oxide by evaporating the at least one metal
from the EAFD and leaving the iron oxide as a residue.
[0018] While aspects of the present invention can be described and
claimed in a particular statutory class, such as the system
statutory class, this is for convenience only and one of skill in
the art will understand that each aspect of the present invention
can be described and claimed in any statutory class. Unless
otherwise expressly stated, it is in no way intended that any
method or aspect set forth herein be construed as requiring that
its steps be performed in a specific order. Accordingly, where a
method claim does not specifically state in the claims or
descriptions that the steps are to be limited to a specific order,
it is no way intended that an order be inferred, in any respect.
This holds for any possible non-express basis for interpretation,
including matters of logic with respect to arrangement of steps or
operational flow, plain meaning derived from grammatical
organization or punctuation, or the number or type of aspects
described in the specification.
[0019] Additional advantages of the invention will be set forth in
part in the description which follows, and in part will be obvious
from the description, or can be learned by practice of the
invention. The advantages of the invention will be realized and
attained by means of the elements and combinations particularly
pointed out in the appended claims. It is to be understood that
both the foregoing general description and the following detailed
description are exemplary and explanatory only and are not
restrictive of the invention, as claimed.
BRIEF DESCRIPTION OF THE FIGURES
[0020] The accompanying figures, which are incorporated in and
constitute a part of this specification, illustrate several aspects
and together with the description serve to explain the principles
of the invention.
[0021] FIG. 1 shows a flow diagram for the Caustic Soda Leaching
Process for the extraction of zinc from EAFD of one aspect of the
invention herein.
[0022] FIG. 2 shows the relationship between the weight loss from a
BHD pellet and the temperature at which the pellet is sintered in a
N.sub.2 atmosphere for one aspect of the invention herein.
[0023] FIG. 3 shows the relationship between the weight % content
of Zn remaining in a BHD pellet after sintering at various
temperatures in a N.sub.2 atmosphere for one aspect of the
invention herein.
[0024] FIG. 4 shows the relationship between the Zn and Pb content
of pellets sintered at various temperatures under nitrogen for one
aspect of the invention herein.
[0025] FIG. 5 shows the Zn and Pb content of vapors extracted from
BHD pellets sintered under N.sub.2 at various temperatures for one
aspect of the invention herein.
[0026] FIG. 6 shows the relationship between the weight of Zn
removed from a BHD pellet sintered in a N.sub.2 atmosphere at
various temperatures for one aspect of the invention herein.
[0027] FIG. 7 shows the weight loss of Pb, Na, K, and Cl from a BHD
pellet sintered at various temperatures under N.sub.2 for one
aspect of the invention herein.
DESCRIPTION
[0028] The present invention can be understood more readily by
reference to the following detailed description of the invention
and the Examples included therein.
[0029] Before the present compounds, compositions, articles,
systems, devices, and/or methods are disclosed and described, it is
to be understood that they are not limited to specific synthetic
methods unless otherwise specified, or to particular reagents
unless otherwise specified, as such may, of course, vary. It is
also to be understood that the terminology used herein is for the
purpose of describing particular aspects only and is not intended
to be limiting. Although any methods and materials similar or
equivalent to those described herein can be used in the practice or
testing of the present invention, example methods and materials are
now described.
[0030] All publications mentioned herein are incorporated herein by
reference to disclose and describe the methods and/or materials in
connection with which the publications are cited. The publications
discussed herein are provided solely for their disclosure prior to
the filing date of the present application. Nothing herein is to be
construed as an admission that the present invention is not
entitled to antedate such publication by virtue of prior invention.
Further, the dates of publication provided herein can be different
from the actual publication dates, which can require independent
confirmation.
A. DEFINITIONS
[0031] As used in the specification and the appended claims, the
singular forms "a," "an" and "the" include plural referents unless
the context clearly dictates otherwise. Thus, for example,
reference to "a functional group," "an alkyl," or "a residue"
includes mixtures of two or more such functional groups, alkyls, or
residues, and the like.
[0032] Ranges can be expressed herein as from "about" one
particular value, and/or to "about" another particular value. When
such a range is expressed, a further aspect includes from the one
particular value and/or to the other particular value. Similarly,
when values are expressed as approximations, by use of the
antecedent "about," it will be understood that the particular value
forms a further aspect. It will be further understood that the
endpoints of each of the ranges are significant both in relation to
the other endpoint, and independently of the other endpoint. It is
also understood that there are a number of values disclosed herein,
and that each value is also herein disclosed as "about" that
particular value in addition to the value itself. For example, if
the value "10" is disclosed, then "about 10" is also disclosed. It
is also understood that each unit between two particular units are
also disclosed. For example, if 10 and 15 are disclosed, then 11,
12, 13, and 14 are also disclosed.
[0033] References in the specification and concluding claims to
parts by weight of a particular element or component in a
composition denotes the weight relationship between the element or
component and any other elements or components in the composition
or article for which a part by weight is expressed. Thus, in a
compound containing 2 parts by weight of component X and 5 parts by
weight component Y, X and Y are present at a weight ratio of 2:5,
and are present in such ratio regardless of whether additional
components are contained in the compound.
[0034] A weight percent (wt. %) of a component, unless specifically
stated to the contrary, is based on the total weight of the
formulation or composition in which the component is included.
[0035] As used herein, the terms "optional" or "optionally" means
that the subsequently described event or circumstance can or cannot
occur, and that the description includes instances where said event
or circumstance occurs and instances where it does not.
[0036] Unless otherwise expressly stated, it is in no way intended
that any method set forth herein be construed as requiring that its
steps be performed in a specific order. Accordingly, where a method
claim does not actually recite an order to be followed by its steps
or it is not otherwise specifically stated in the claims or
descriptions that the steps are to be limited to a specific order,
it is no way intended that an order be inferred, in any respect.
This holds for any possible non-express basis for interpretation,
including: matters of logic with respect to arrangement of steps or
operational flow; plain meaning derived from grammatical
organization or punctuation; and the number or type of embodiments
described in the specification.
[0037] It is understood that the compositions disclosed herein have
certain functions. Disclosed herein are certain structural
requirements for performing the disclosed functions and it is
understood that there are a variety of structures that can perform
the same function that are related to the disclosed structures, and
that these structures will typically achieve the same result.
[0038] As used herein, the term "green strength testing" typically
refers to a test that measures the ability of green pellets to
remain intact during handling. In one test in this disclosure, a
pellet is dropped a number of times from the height of 30 cm on a
flat steel plate until it breaks. As used herein, the term "drop
number" typically refers to the number of times before it
breaks.
[0039] As used herein, the term "green pellets" typically refers to
the pellets comprising moisture. The term can refer to pellets
produced by balling action in a rotating disk or drum comprising
moisture before drying or heating.
[0040] As used herein, the terms "sintered" or "sintering"
typically refers to heating to a specific temperature and holding
for a specific time in a furnace in certain gaseous or air
atmosphere.
[0041] As used herein, the term "binder" typically refers to a
compound or composition that aids in binding the powder and
formulation of pellets, which can be spherical, in the presence of
a specific amount of water. Such binding preparation can be, for
example, during balling in a rotating disk or drum.
[0042] As used herein, the term "inert gas atmosphere" typically
refers to an atmosphere of non-reactive gases such as nitrogen,
argon, xenon, or krypton, and the like.
[0043] As used herein, the term or phrase "electric arc furnace
dust" or "EAFD" is a term of art and refers to a solid by-product
or material produced from a furnace steelmaking process, and is
intended to encompass by-products and materials generated from all
steelmaking operation phases and sources, such as, for example,
scrap iron furnaces or sponge iron furnaces.
[0044] As used herein, the term or phrase "bag house dust" or "BHD"
is a term of art and refers to a type of electric arc furnace dust
generated in Saudi Arabia, which may, in various aspects, have
similar or differing chemical compositions than electric arc
furnace dusts produced from different countries. The bag house dust
can be collected in a bag house, also called a bag house
filter.
ABBREVIATIONS AND ACRONYMS
BHD Bag House Dust
[0045] .degree. C. degrees Celsius
C&S Analyzers Carbon & Sulphur Analyzer
[0046] DRI Direct reduced iron
EAF Electric Arc Furnace
EAFD Electric Arc Furnace Dust
[0047] g gram(s) IEPA International environmental protection
agencies kgf Kilogram force XRD techniques X-Ray Diffraction
XRF X-Ray Fluorescence
[0048] 1. Electric Arc Furnace Dust (EAFD)
[0049] In various aspects, the disclosed compositions comprise
by-products produced from a steelmaking process. In one aspect, the
disclosed compositions comprise by-products produced from an
electric steelmaking process. In a further aspect, the by-products
comprise electric arc furnace dust (EAFD). In a still further
aspect, the electric arc furnace dust (EAFD) comprises EAFD
produced in various regions, for example, EAFD from North America
or Europe or the Middle East. In a yet further aspect, the EAFD
comprises EAFD of varying compositions depending on the type of
scrap used, type of additives used during the production stage and
the type of steel manufacture. For example, in one aspect, the EAFD
comprises EAFD generated in Saudi Arabia, also referred to as bag
house dust (BHD). In a further aspect, the EAFD comprises
unstabilized, untreated EAFD. In a still further aspect, the EAFD
comprises stabilized, untreated EAFD. In a yet further aspect, the
EAFD comprises treated EAFD. In an even further aspect, the
disclosed compositions comprise at least one additional by-product,
for example, fly ash, blast furnace slag, or silica fume, or the
like. An exemplary, non-limiting EAFD comprises one or more
components comprising Fe, Zn, Pd, Cr, Cd, Mn, Cu, Si, Ca, Mg, Al,
C, Na, or K or a mixture thereof. When the component is present,
the EAFD comprises Fe in an amount ranging from 10 wt % to 60 wt %,
Zn in an amount ranging from 2 wt % to 50 wt %, Pd in an amount
ranging from 0.40 wt % to 15.14 wt %, Cr in an amount ranging from
0.2 wt % to 11 wt %, Cd in an amount ranging from 0.01 wt % to 0.3
wt %, Mn in an amount ranging from 1 wt % to 5 wt %, Cu in an
amount ranging from 0.01 wt % to 0.3 wt %, Si in an amount ranging
from 1 wt % to 5 wt %, Ca in an amount ranging from 1 wt % to 25 wt
%, Mg in an amount ranging from 1 wt % to 12 wt %, Al in an amount
ranging from 0.1 wt % to 4 wt %, C in an amount ranging from 0.11
wt % to 2.36 wt %, Na in an amount ranging from 0.5 wt % to 5 wt %,
and K in an amount ranging from 0.35 wt % to 7 wt %.
[0050] In one aspect, a typical chemical composition of the EAFD is
as follows:
TABLE-US-00001 Elements Wt % Fe.sub.3O.sub.4 47.44 ZnO 19.36
Na.sub.2O 2.52 MgO 5.85 CaO 6.63 K.sub.2O 4.64 SiO.sub.2 4.75 Cl
1.70 PbO 1.89 MnO 1.79 SO.sub.3 1.16 Al.sub.2O.sub.3 1.34 Cu 0.26 C
0.72
[0051] In one aspect, an exemplary, non-limiting composition of
EAFD can include 29 wt % of Zn, 0.3 wt % of Cu, 4 wt % of Pb, 0.07
wt % of Cd, 25 wt % of Fe, 4 wt % of Cl, 3 wt % of MnO, and 3 wt %
of SiO.sub.2.
[0052] In one aspect, an exemplary, non-limiting EAFD, as measured
using optical emission via Inductive Coupled Plasma (ICP), X-ray
diffractometry (XRD), and Mossbauer spectroscopy analysis exhibits
the following composition: ZnFe.sub.2O.sub.4, Fe.sub.3O.sub.4,
MgFe.sub.2O.sub.4, FeCr.sub.2O.sub.4, CaO.15Fe.sub.2.85O.sub.4,
MgO, Mn.sub.3O.sub.4, SiO.sub.2, and ZnO. In a further aspect, most
of the elements in the EAFD are in the oxide form.
[0053] In various aspects, the disclosed methods and compositions
comprising EAFD provide numerous environmental advantages. In one
aspect, the use of EAFD according to the present invention provides
an effective means of EAFD disposal. In a further aspect, the
disclosed methods and compositions, by utilizing EAFD, reduce
potential environment problems associated with EAFD disposal. In a
yet further aspect, the disclosed methods and compositions
eliminate the need to dispose of EAFD in a landfill. In a still
further aspect, the reduction in EAFD disposal frees landfill
space.
[0054] In another aspect, the disclosed methods and compositions
utilize untreated EAFD, thereby avoiding the cost associated with
pretreatment of EAFD.
[0055] 2. Method for Recovering Metal Oxide from EAFD
[0056] In one aspect, the invention comprises a method for
preparing Electric Arc Furnace dust (EAFD) for metal recovery,
comprising: [0057] a) mixing the EAFD comprising zinc oxide or lead
oxide, or a mixture of both with a liquid and a binder to produce
an EAFD mixture; [0058] b) producing a shaped EAFD pellet; and
[0059] c) drying the shaped EAFD pellet.
[0060] The method for preparing EAFD for metal recovery can use
methods, techniques, or compositions from the other disclosed
methods.
[0061] In one aspect, the shaped EAFD pellet can be produced in a
rotating balling disc or a drum.
[0062] In a further aspect, the zinc oxide or lead oxide, or a
mixture of both can be present in an amount from about 0.01 wt % to
about 50 wt %, based on the total weight of the EAFD, including
exemplary values of 0.40 wt %, 0.50 wt %, 2 wt %, 4 wt %, 6 wt %, 8
wt %, 10 wt %, 13 wt %, 15 wt %, 17 wt %, 20 wt %, 23 wt %, 25 wt
%, 27 wt %, 30 wt %, 33 wt %, 35 wt %, 37 wt %, 40 wt %, 43 wt %,
45 wt %, 46 wt %, and 48 wt %. In a still further aspect, the zinc
oxide or lead oxide, or a mixture of both can be present in a range
derived from any two of the above listed exemplary wt %. For
example, the zinc oxide or lead oxide, or a mixture of both can be
present in an amount from about 0.40 wt % to about 17 wt %.
[0063] In a further aspect, the EAFD is BHD. In another aspect, the
EAFD dust can come from a steel plant or other source. In one
aspect, the EAFD can be dried in the sun to gain a sufficient
strength so that these pellets can be transported.
[0064] In a further aspect, the liquid comprises water.
[0065] In a further aspect, the liquid can be present in an amount
from about 6.0 wt % to about 12 wt %, based on the total weight of
the EAFD mixture, which includes the binder and liquid, including
exemplary values of 6.0 wt %, 8.0 wt %, 10 wt %, and 12 wt %. In a
still further aspect, the liquid can be present in a range derived
from any two of the above listed exemplary wt %. For example, the
liquid can be present in an amount from about 8.0 wt % to about
10.0 wt %, 6 wt % to 12 wt %, or 6 wt % to 8 wt %.
[0066] In a further aspect, the binder comprises carbon, burnt
lime, bentonite, or molasses, or a mixture thereof. In a still
further aspect, the binder is bentonite. In a yet further aspect,
the binder is molasses.
[0067] In a further aspect, the binder can be present in an amount
from about 0.01 wt % to about 5.0 wt %, based on the total weight
of the EAFD mixture, which includes the binder and liquid,
including the exemplary values of 0.25 wt %, 0.50 wt %, 0.75 wt %,
1.0 wt %, 1.5 wt %, 2.0 wt %, 2.5 wt %, 3 wt %, 3.5 wt %, 4 wt %,
and 4.5 wt %. In a still further aspect, the binder can be present
in a range derived from any two of the above listed exemplary wt %.
For example, the binder can be present in an amount from about 0.25
wt % to about 1.0 wt %.
[0068] In a further aspect, the binder comprises carbon in an
amount from about 10 wt % to about 25 wt % based on the total
weight of the binder, including the exemplary values of 12 wt %, 14
wt %, 16 wt %, 18 wt %, 20 wt %, 22 wt %, and 24 wt %. In a still
further aspect, the binder comprises carbon in a range derived from
any two of the above listed exemplary wt %. For example, the binder
can comprise carbon in an amount from about 16 wt % to about 18 wt
% based on the total weight of the binder.
[0069] In a further aspect, the binder comprises molasses in an
amount from about 0.01 wt % to about 5.0 wt %, based on the total
weight of the EAFD mixture, including the exemplary values of 0.5
wt %, 1 wt %, 1.5 wt %, 2 wt %, 2.5 wt %, 3 wt %, 3.5 wt %, 4 wt %,
and 4.5 wt %. In a still further aspect, the binder comprises
molasses in a range derived from any two of the above listed
exemplary wt %. For example, the binder can comprise molasses in an
amount from about 1 wt % to about 2 wt %. In one aspect, the binder
is molasses.
[0070] In one aspect, the bentonite, which is a trade name of a
binder comprising sodium potassium silicate, is used in the binder
herein. The binder can comprise bentonite in an amount ranging from
0 wt % to 4.5 wt %, based on the total weight of the EAFD mixture,
which includes the binder and liquid, including exemplary values
0.5 wt %, 1 wt %, 1.5 wt %, 2 wt %, 2.5 wt %, 3 wt %, 3.5 wt %, and
4 wt %. In a still further aspect, the binder comprises bentonite
in a range derived from any two of the above listed exemplary wt %.
For example, the binder can comprise bentonite in a range from 0.5
wt % to 4 wt % based on the total weight of the EAFD. In one
aspect, the binder is bentonite.
[0071] In a further aspect, the EAFD can be mixed with the liquid
and binder using conventional methods such as with an intensive
mixer, such as a ROB Erich mixer or any other mixing equipment.
[0072] In one aspect, the method comprises producing an EAFD
mixture. In another aspect, the EAFD mixture is a homogeneous
composition.
[0073] In a further aspect, the EAFD pellet can be produced using
any conventional method to produce a pellet, such as with a pan
pelletizer or a drum pelletizer. In one aspect, forming a pellet
can be desirable as a form to contain the dust in a leach-proof
matrix for storing and disposing the EAFD.
[0074] In a further aspect, the EAFD pellet can be dried using any
conventional method for drying, such as drying in the sun for a
period of 1-4 days or heating in a drying oven.
[0075] In a further aspect, the average pellet size can range from
about 7 mm to 18 mm, including exemplary values of 8 mm, 9 mm, 10
mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, and 17 mm. In a still
further aspect, the average pellet size can be in a range derived
from any two of the above listed exemplary values. For example, the
average pellet size can range from 8 mm to 17 mm.
[0076] In one aspect, the pellet is a spherical shape. In another
aspect, the pellet can be any conventional pellet shape.
[0077] In one aspect, the pellet is produced using conventional
methods. In another aspect, the pelletizing comprises the steps of
grinding, sieving, mixing, agglomeration, binder optimization, and
sintering. In a further aspect, the pelletizing uses a R02 Elrich
mixer followed by pelletization on a disc pelletizer to produce the
pellets.
[0078] The pellet has improved properties in physical, mechanical,
chemical, and metallurgical properties. The pellet can be used in
the method disclosed herein for recovering zinc or zinc oxide from
EAFD. The pellet can be used as a way to transport the EAFD for
metal recovery. The pellet can be used in the method disclosed
herein for recovering lead, chlorine, sodium, or potassium, or a
mixture thereof. The pellet can be used in the method disclosed
herein for recovering iron oxide.
[0079] 3. Method for Recovering Zinc/Zinc Oxide/Zinc Complex from
EAFD
[0080] In one aspect, the invention comprises a method for
recovering zinc from Electric Arc Furnace dust (EAFD), comprising:
[0081] a) heating the EAFD comprising at least one metal comprising
zinc in an inert gas atmosphere at a temperature ranging from
700.degree. C. to 1100.degree. C.; and [0082] b) evaporating the at
least one metal comprising zinc from the EAFD and collecting the at
least one metal.
[0083] The method for recovering zinc from EAFD can use methods,
techniques, or compositions from the other disclosed methods.
[0084] FIG. 1 shows a flow diagram for the Caustic Soda Leaching
Process for the extraction of zinc from EAFD of one aspect of the
invention herein. FIG. 1 shows the inventive process for recovering
the zinc using heating and evaporation.
[0085] In a further aspect, the zinc comprises zinc metal, zinc
oxide or a complex of zinc and another metal oxide, or a mixture
thereof. In a still further aspect, the zinc comprises zinc oxide.
In yet a further aspect, the zinc comprises a complex of zinc and a
metal oxide. In another aspect, the metal oxide of the complex
comprises iron oxide. The complex of zinc and iron oxide can be
zinc ferrite (ZnO.Fe.sub.2O.sub.3, franklinite). In one aspect, the
zinc can comprise approximately 50 wt % in the zinc ferrite form
based on the total weight of the zinc. The removal of the zinc from
the EAFD can reduce the environmental liability and/or can create a
value-added product by collecting the zinc.
[0086] In a further aspect, the zinc can be present in an amount
from about 0.01 wt % to about 50 wt %, based on the total weight of
the EAFD, including the exemplary values of including exemplary
values of 0.40 wt %, 0.50 wt %, 2 wt %, 4 wt %, 6 wt %, 8 wt %, 10
wt %, 13 wt %, 15 wt %, 17 wt %, 20 wt %, 23 wt %, 25 wt %, 27 wt
%, 30 wt %, 33 wt %, 35 wt %, 37 wt %, 40 wt %, 43 wt %, 45 wt %,
46 wt %, and 48 wt %. In a still further aspect, the zinc can be
present in a range derived from any two of the above listed
exemplary wt %. For example, the zinc can be present in an amount
from about 2.0 wt % to about 46 wt %.
[0087] In a further aspect, the EAFD is BHD. In another aspect, the
EAFD can come from a steel plant or other source. In a yet further
aspect, the EAFD is in the form of a pellet.
[0088] In a further aspect, the average EAFD pellet size can range
from about 7 mm to 18 mm, including exemplary values of 8 mm, 9 mm,
10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, and 17 mm. In a
still further aspect, the average pellet size can be in a range
derived from any two of the above listed exemplary values. For
example, the average pellet size can range from 8 mm to 17 mm.
[0089] In a further aspect, the inert gas comprises N.sub.2, Ar,
CO, or H.sub.2, or a mixture thereof. In a still further aspect,
the inert gas comprises Ar, CO, or H.sub.2, or a mixture thereof.
In yet a further aspect, the inert gas comprises CO or H.sub.2, or
a mixture thereof. In an even further aspect, the inert gas is
N.sub.2. In a still further aspect, the inert gas is Ar. In yet a
further aspect, the inert gas is CO. In an even further aspect, the
inert gas is H.sub.2.
[0090] In a further aspect, the EAFD can be heated using a Static
Reduction Reactor or any other suitable heating device.
[0091] In a further aspect, the Static Reduction Reactor further
comprises [0092] a) a system to supply and regulate the gases,
[0093] b) a reductible tube of heat resistant steel, [0094] c) a
weighing device to determine the oxygen loss at regular intervals,
[0095] d) an electrically heated furnace to heat the test portion
to the specified temperature, and/or [0096] e) a chart recorder to
record the weight loss and a control panel to control the flow and
pressure of gas supplied.
[0097] In a further aspect, the EAFD can be heated at a temperature
of from about 700.degree. C. to about 1100.degree. C., including
the exemplary values of 750.degree. C., 800.degree. C., 900.degree.
C., 1000.degree. C., and 1050.degree. C. In a still further aspect,
the EAFD can be heated in a range derived from any two of the above
listed exemplary temperatures. For example, the EAFD pellets can be
heated at a temperature from about 750.degree. C. to about
1050.degree. C.
[0098] In a further aspect, the at least one metal comprising zinc
was evaporated until there is no more or substantially no more loss
of weight from the EAFD source.
[0099] In one aspect, the zinc is evaporated and exits with at
least one exhaust gas. The gases can be cooled and can be filtered
in a cloth filter to collect a powder. The powder can comprise Zn
and/or ZnO. The powder is filtered from the gas which can comprise
Pb, Na, and/or K. The Pb, Na, and/or K can be in a compound with
chlorine. In one aspect, the Na or K in the form of NaCl or KCl,
respectively can be dissolved in water and removed.
[0100] In a further aspect, the invention further comprises
re-oxidizing the zinc to form zinc oxide and collecting the zinc
oxide.
[0101] 4. Method for Recovering an Impurity
[0102] In a further aspect, the invention comprises a method for
recovering an impurity from Electric Arc Furnace dust (EAFD),
comprising: [0103] a) heating the EAFD comprising an impurity in an
inert gas atmosphere at a temperature ranging from 700.degree. C.
to 1100.degree. C.; and [0104] b) evaporating the impurity from the
EAFD and collecting the impurity.
[0105] The method for recovering an impurity from EAFD can use
methods, techniques, or compositions from the other disclosed
methods.
[0106] In a further aspect, the impurity comprises lead, chlorine,
sodium, or potassium, or a mixture thereof. In a still further
aspect, the impurity comprises lead, chlorine, or sodium, or a
mixture thereof. In yet a further aspect, the impurity comprises
lead or chlorine, or a mixture thereof. In an even further aspect,
the impurity is lead. In a still further aspect, the impurity is
chlorine. In yet a further aspect, the impurity is sodium. In an
even further aspect, the impurity is potassium. The removal of the
impurity from EAFD can reduce the environmental liability and/or
can create a value-added product by collecting the metal.
[0107] In a further aspect, the impurity can be present in an
amount from about 0.01 wt % to about 20 wt %, based on the total
weight of the EAFD, including the exemplary values of 0.35 wt %,
0.40 wt %, 0.50 wt %, 1.8 wt %, 3.0 wt %, 4 wt %, 5 wt %, 6 wt %, 7
wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %,
15 wt %, 16 wt %, 17 wt %, 18 wt %, and 19 wt %. In a still further
aspect, the impurity can be present in a range derived from any two
of the above listed exemplary wt %. For example, the impurity can
be present in an amount from about 0.5 wt % to about 1.8 wt %.
[0108] In a further aspect, the impurity further comprises
chromium, cadmium, manganese, copper, silicon, calcium, magnesium,
aluminum, carbon, or sulfur, or a mixture thereof. In a still
further aspect, the impurity further comprises chromium, cadmium,
manganese, copper, silicon, calcium, or magnesium, or a mixture
thereof. In yet a further aspect, the impurity further comprises
chromium, cadmium, manganese, silicon, carbon, or magnesium, or a
mixture thereof. In an even further aspect, the impurity further
comprises calcium or magnesium, or a mixture thereof. In an even
further aspect, the impurity further comprises calcium.
[0109] In a further aspect, the EAFD is BHD. In another aspect, the
EAFD is in the form of a pellet.
[0110] In a further aspect, the average EAFD pellet size can range
from about 7 mm to 18 mm, including exemplary values of 8 mm, 9 mm,
10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, and 17 mm. In a
still further aspect, the average pellet size can be in a range
derived from any two of the above listed exemplary values. For
example, the average pellet size can range from 8 mm to 17 mm.
[0111] In a further aspect, the inert gas comprises N.sub.2, Ar,
CO, or H.sub.2, or a mixture thereof. In a still further aspect,
the inert gas comprises Ar, CO, or H.sub.2, or a mixture thereof.
In yet a further aspect, the inert gas comprises CO or H.sub.2, or
a mixture thereof. In an even further aspect, the inert gas is
N.sub.2. In a still further aspect, the inert gas is Ar. In yet a
further aspect, the inert gas is CO. In an even further aspect, the
inert gas is H.sub.2.
[0112] In a further aspect, the EAFD can be heated using a Static
Reduction Reactor.
[0113] In a further aspect, the Static Reduction Reactor further
comprises [0114] a) a system to supply and regulate the gases,
[0115] b) a reductible tube of heat resistant steel, [0116] c) a
weighing device to determine the oxygen loss at regular intervals,
[0117] d) an electrically heated furnace to heat the test portion
to the specified temperature, and/or [0118] e) a chart recorder to
record the weight loss and control panel to control the flow and
pressure of gas supplied.
[0119] In a further aspect, the EAFD pellet can be heated at a
temperature from about 700.degree. C. to about 1100.degree. C.,
including the exemplary values of 750.degree. C., 800.degree. C.,
900.degree. C., 1000.degree. C., and 1050.degree. C. In a still
further aspect, the EAFD pellet can be heated in a range derived
from any two of the above listed exemplary temperatures. For
example, the EAFD pellet can be heated at a temperature from about
750.degree. C. to about 1050.degree. C.
[0120] In one aspect, the metal is evaporated under inert
atmosphere.
[0121] In a further aspect, the at least one metal is evaporated
until there is no more loss of weight.
[0122] In one aspect, the evaporated impurity is collected by
cooling it to form a solid powder condensate and filtering and
collecting in a bag filter.
[0123] 5. Method for Recovering Iron Oxide from EAFD
[0124] In one aspect, the invention comprises a method for
recovering iron oxide from Electric Arc Furnace dust (EAFD),
comprising: [0125] a) heating the EAFD comprising iron oxide and at
least one metal in an inert gas atmosphere at a temperature ranging
from 700.degree. C. to 1100.degree. C.; [0126] b) separating the
iron oxide by evaporating the at least one metal from the EAFD and
leaving the iron oxide as a residue.
[0127] The method for recovering iron oxide from EAFD can use
methods, techniques, or compositions from the other disclosed
methods.
[0128] In a further aspect, the iron can be present as iron oxide
or as a complex of zinc and iron oxide, or a mixture thereof. In a
still further aspect, the iron can be present as iron oxide. In yet
a further aspect, the iron can be present as a complex of zinc and
iron oxide. The removal of the metal from the EAFD can reduce the
environmental liability and/or can create a value-added product by
collecting the iron oxide.
[0129] In a further aspect, the metal further comprises zinc, lead,
chromium, cadmium, manganese, copper, silicon, calcium, magnesium,
aluminum, carbon, sulfur, sodium, potassium, or chlorine, or a
mixture thereof. In a still further aspect, the metal further
comprises zinc, lead, chromium, cadmium, manganese, copper,
silicon, calcium, magnesium, sodium, potassium, or chlorine, or a
mixture thereof. In yet a further aspect, the metal further
comprises zinc, lead, chromium, cadmium, manganese, silicon,
carbon, magnesium, sodium, potassium, or chlorine, or a mixture
thereof. In an even further aspect, the metal further comprises
zinc, lead, sodium, potassium, or chlorine, or a mixture thereof.
In an even further aspect, the metal further comprises zinc, or
lead, or a mixture thereof. In a still further aspect, the metal
further comprises zinc. In yet a further aspect, the metal further
comprises lead.
[0130] In a further aspect, the iron can be present in an amount
from about 0.01 wt % to about 68 wt %, based on the total weight of
the EAFD, including the exemplary values of including exemplary
values of 0.40 wt %, 0.50 wt %, 2 wt %, 4 wt %, 6 wt %, 8 wt %, 10
wt %, 13 wt %, 15 wt %, 17 wt %, 20 wt %, 23 wt %, 25 wt %, 27 wt
%, 30 wt %, 33 wt %, 35 wt %, 37 wt %, 40 wt %, 43 wt %, 45 wt %,
46 wt %, 48 wt %, 50 wt %, 52 wt %, 54 wt %, 56 wt %, 58 wt %, 60
wt %, 62 wt %, 64 wt %, and 66 wt %. In a still further aspect, the
iron can be present in a range derived from any two of the above
listed exemplary wt %. For example, the iron can be present in an
amount from about 10 wt % to about 45 wt %.
[0131] In a further aspect, the other metals detailed above can be
present in an amount from about 0.01 wt % to about 68 wt %, based
on the total weight of the EAFD, including the exemplary values of
including exemplary values of 0.2 wt %, 0.3 wt %, 0.40 wt %, 0.50
wt %, 2 wt %, 4 wt %, 6 wt %, 8 wt %, 10 wt %, 13 wt %, 15 wt %, 17
wt %, 20 wt %, 23 wt %, 25 wt %, 27 wt %, 30 wt %, 33 wt %, 35 wt
%, 37 wt %, 40 wt %, 43 wt %, 45 wt %, 46 wt %, 48 wt %, 50 wt %,
52 wt %, 54 wt %, 56 wt %, 58 wt %, 60 wt %, 62 wt %, 64 wt %, and
66 wt %. In a still further aspect, the other metals detailed above
can be present in a range derived from any two of the above listed
exemplary wt %. For example, the other metals detailed above can be
present in an amount from about 0.01 wt % to about 0.3 wt %.
[0132] In a further aspect, the EAFD is BHD. In another aspect, the
EAFD is in the form of a pellet.
[0133] In a further aspect, the average pellet size can range from
about 7 mm to 18 mm, including exemplary values of 8 mm, 9 mm, 10
mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, and 17 mm. In a still
further aspect, the average pellet size can be in a range derived
from any two of the above listed exemplary values. For example, the
average pellet size can range from 8 mm to 17 mm.
[0134] In a further aspect the inert gas comprises N.sub.2 or Ar or
a mixture thereof. In a further aspect, the inert gas is N.sub.2.
In a still further aspect, the inert gas is Ar.
[0135] In a further aspect, the EAFD can be heated using a Static
Reduction Reactor.
[0136] In a further aspect, the Static Reduction Reactor further
comprises [0137] a) a system to supply and regulate the gases,
[0138] b) a reductible tube of heat resistant steel, [0139] c) a
weighing device to determine the oxygen loss at regular intervals,
[0140] d) an electrically heated furnace to heat the test portion
to the specified temperature, and/or [0141] e) a chart recorder to
record the weight loss and control panel to control the flow and
pressure of gas supplied.
[0142] In a further aspect, the EAFD can be heated at a temperature
from about 700.degree. C. to about 1100.degree. C., including the
exemplary values of 750.degree. C., 800.degree. C., 900.degree. C.,
1000.degree. C., and 1050.degree. C. In a still further aspect, the
EAFD can be heated in a range derived from any two of the above
listed exemplary temperatures. For example, the EAFD can be heated
at a temperature from about 750.degree. C. to about 1050.degree.
C.
[0143] In one aspect, the at least one metal comprises zinc, zinc
oxide, and/or zinc ferrite. In a further aspect, the zinc oxide
and/or zinc ferrite can be dissociated. In another aspect, the zinc
is evaporated.
[0144] In one aspect, the iron oxide is separated from the oxide of
calcium, magnesium, silicon, and/or aluminum. In another aspect,
the oxide of calcium, magnesium, silicon, and/or aluminum is left
behind in the pellet.
[0145] In another aspect, the residual pellet comprises iron oxide
and/or the oxide of calcium, silicon, aluminum, and/or magnesium.
In a further aspect, the pellet can be collected from the sintering
tube after cooling.
[0146] In one aspect, the iron oxide is present in a purity of 45
wt % to 80 wt % based on the total weight of the EAFD, including
exemplary values of 50 wt %, 55 wt %, 60 wt %, 65 wt %, 70 wt %,
and 75 wt %. In a still further aspect, the iron oxide is present
in a purity derived from any two of the above listed exemplary wt
%. For example, the iron oxide is present in a purity of 55 wt % to
70 wt %.
B. ASPECTS
[0147] The disclosed compositions and methods include at least the
following aspects.
[0148] Aspect 1: A method for preparing Electric Arc Furnace dust
(EAFD) for metal recovery, comprising: [0149] a) mixing the EAFD
comprising zinc oxide or lead oxide, or a mixture of both, with a
liquid and a binder to produce an EAFD mixture; [0150] b) producing
a shaped EAFD pellet; and [0151] c) drying the shaped EAFD
pellet.
[0152] Aspect 2: The method according to aspect 1, wherein the EAFD
is Bag House Dust (BHD).
[0153] Aspect 3: The method according to any one of aspects 1-2,
wherein the metal oxide is zinc oxide.
[0154] Aspect 4: The method according to any one of aspects 1-3,
wherein the metal oxide is lead oxide.
[0155] Aspect 5: The method according to any one of aspects 1-4,
wherein the liquid is water.
[0156] Aspect 6: The method according to any one of aspects 1-5,
wherein the liquid is present in an amount from about 6.0 wt % to
12.0 wt %, based on the total weight of the EAFD mixture.
[0157] Aspect 7: The method according to any one of aspects 1-6,
wherein the liquid is present in amount from about 6.0 wt % to 10.0
wt %, based on the total weight of the EAFD mixture.
[0158] Aspect 8: The method according to any one of aspects 1-7,
wherein the liquid is present in amount from about 6.0 wt % to 8.0
wt %, based on the total weight of the EAFD mixture.
[0159] Aspect 9: The method according to any one of aspects 1-8,
wherein the binder is present in an amount from about 0.01 wt % to
about 5.0 wt %, based on the total weight of the EAFD mixture.
[0160] Aspect 10: The method according to any one of aspects 1-9,
wherein the binder is present in an amount of about 0.25 wt %,
based on the total weight of the EAFD mixture.
[0161] Aspect 11: The method according to any one of aspects 1-10,
wherein the binder is present in an amount of about 0.50 wt %,
based on the total weight of the EAFD mixture.
[0162] Aspect 12: The method according to any one of aspects 1-11,
wherein the binder is present in an amount of about 0.75 wt %,
based on the total weight of the EAFD mixture.
[0163] Aspect 13: The method according to any one of aspect 1-12,
wherein the binder is present in an amount of about 1.00 wt %,
based on the total weight of the EAFD mixture.
[0164] Aspect 14: The method according to any one of aspects 1-13,
wherein the binder is present in an amount of about 1.50 wt %,
based on the total weight of the EAFD mixture.
[0165] Aspect 15: The method according to any one of aspects 1-14,
wherein the binder is present in an amount of about 2.00 wt %,
based on the total weight of the EAFD mixture.
[0166] Aspect 16: The method according to any one of aspects 1-15,
wherein the average pellet size is from about 7.0 to 18 mm.
[0167] Aspect 17: A method for recovering zinc from Electric Arc
Furnace dust (EAFD), comprising: [0168] a) heating the EAFD
comprising at least one metal comprising zinc in an inert gas
atmosphere at a temperature ranging from 700.degree. C. to
1100.degree. C.; and [0169] b) evaporating the at least one metal
comprising zinc from the EAFD and collecting the at least one
metal.
[0170] Aspect 18: The method according to aspect 17, wherein the at
least one metal is zinc.
[0171] Aspect 19: The method according to any one of aspects 17-18,
wherein the EAFD is Bag House Dust (BHD).
[0172] Aspect 20: The method according to any one of aspects 17-19,
wherein the inert gas comprises N.sub.2 or Ar, or a mixture
thereof.
[0173] Aspect 21: The method according to any one of aspects 17-20,
wherein the inert gas comprises Ar.
[0174] Aspect 22: The method according to any one of aspects 17-21,
wherein the inert gas is N.sub.2.
[0175] Aspect 23: The method according to any one of aspects 17-22,
wherein the method comprises re-oxidizing the zinc to form zinc
oxide and collecting the zinc oxide.
[0176] Aspect 24: The method according to any one of aspects 17-23,
wherein the EAFD is a pellet.
[0177] Aspect 25: A method for recovering an impurity from Electric
Arc Furnace dust (EAFD), comprising: [0178] a) heating the EAFD
comprising an impurity in an inert gas atmosphere at a temperature
ranging from 700.degree. C. to 1100.degree. C.; and [0179] b)
evaporating the impurity from the EAFD and collecting the
impurity.
[0180] Aspect 26: The method according to aspect 25, wherein the
EAFD is Bag House Dust (BHD).
[0181] Aspect 27: The method according to any one of aspects 25-26,
wherein EAFD is in the form of a pellet.
[0182] Aspect 28: The method according to any one of aspects 25-27,
wherein the impurity comprises lead, chlorine, or sodium, or a
mixture thereof.
[0183] Aspect 29: The method according to any one of aspects 25-28,
wherein the impurity comprises lead, or chlorine, or a mixture
thereof.
[0184] Aspect 30: The method according to any one of aspects 25-29,
wherein the impurity comprises lead.
[0185] Aspect 31: The method according to any one of aspects 25-30,
wherein the impurity comprises chlorine.
[0186] Aspect 32: The method according to any one of aspects 25-31,
wherein the impurity comprises sodium.
[0187] Aspect 33: The method according to any one of aspects 25-32,
wherein the impurity comprises potassium.
[0188] Aspect 34: The method according to any one of aspects 25-33,
wherein the inert gas comprises N.sub.2 or Ar, or a mixture
thereof.
[0189] Aspect 35: The method according to any one of aspects 25-34,
wherein the inert gas is N.sub.2.
[0190] Aspect 36: The method according to any one of aspects 25-35,
wherein the inert gas is Ar.
[0191] Aspect 37: The method according to any one of aspects 28-36,
wherein the method comprises re-oxidizing the lead to form lead
oxide and collecting the lead oxide.
[0192] Aspect 38: The method according to any one of aspects 25-37,
wherein the average pellet size is from about 7.0 to 18 mm.
[0193] Aspect 39: A method for recovering iron oxide from Electric
Arc Furnace dust (EAFD), comprising: [0194] a) heating the EAFD
comprising iron oxide and at least one metal in an inert gas
atmosphere at a temperature ranging from 700.degree. C. to
1100.degree. C.; and [0195] b) separating the iron oxide by
evaporating the at least one metal from the EAFD and leaving the
iron oxide as a residue.
[0196] Aspect 40: The method according to aspect 39, wherein the
EAFD is Bag House Dust (BHD).
[0197] Aspect 41: The method according to any one of aspects 39-40,
wherein the inert gas comprises N.sub.2 or Ar, or a mixture
thereof.
[0198] Aspect 42: The method according to any one of aspects 39-41,
wherein the inert gas is N.sub.2.
[0199] Aspect 43: The method according to any one of aspects 39-42,
wherein the inert gas is Ar.
[0200] Aspect 44: The method according to any one of aspects 39-43,
EAFD is in the form of a pellet.
[0201] Aspect 45: The method according to any one of aspects 39-44,
wherein the at least one metal comprises zinc, lead, chromium,
cadmium, manganese, copper, silicon, calcium, magnesium, aluminum,
carbon, sulfur, sodium, potassium, or chlorine, or a mixture
thereof.
C. EXPERIMENTAL
[0202] The following examples are put forth so as to provide those
of ordinary skill in the art with a complete disclosure and
description of how the compounds, compositions, articles, devices
and/or methods claimed herein are made and evaluated, and are
intended to be purely exemplary of the invention and are not
intended to limit the scope of what the inventors regard as their
invention. Efforts have been made to ensure accuracy with respect
to numbers (e.g., amounts, temperature, etc.), but some errors and
deviations should be accounted for. Unless indicated otherwise,
parts are parts by weight, temperature is in .degree. C. or is at
ambient temperature, and pressure is at or near atmospheric.
[0203] Several methods for preparing the compounds of this
invention are illustrated in the following Examples. Starting
materials and the requisite intermediates are in some cases
commercially available, or can be prepared according to literature
procedures or as illustrated herein.
[0204] The following exemplary compounds of the invention were
synthesized. The Examples are provided herein to illustrate the
invention, and should not be construed as limiting the invention in
any way. The Examples are typically depicted in free base form,
according to the IUPAC naming convention. However, some of the
Examples were obtained or isolated in salt form.
1. Example 1
a. Preparation and Evaluation of Pellets
[0205] Pelletizing included the steps of grinding and sieving,
mixing, agglomeration, green strength testing, and binder
optimization; evaluation included sintering, and testing of the
pellets compressive strength after heating. BHD contained more than
95% of particle size less than 90 microns, which did not require
any further grinding, was used. Only sieving was conducted to
remove the dust fraction >90 microns. Bentonite and burnt lime
were used as binders. The optimum binder addition was determined
for each of the mixtures. All the samples were pelletized and
evaluated to determine the physical and metallurgical properties of
the pellets produced.
[0206] Binder additions of 0.25, 0.50, 0.75, 1.00, 1.5 and 2 wt %
binder, based on the total EAFD weight, respectively were added to
determine the optimum binder content. Batches (3-5 kg) of each
sample were premixed with the different binder additives in an RO2
Elrich mixer followed by pelletization on a disc pelletizer to
produce pellets with size range of 09 to 16 mm. Water, 8-10% by wt.
based on the total weight of the EAFD, was added before mixing. All
the pellets samples were dried in the sun in open air for a couple
of days. The drop number and compression tests were conducted on 12
different pellets for each type of sample produced to determine the
binder additive with optimum pellet strength. The average, minimum,
maximum strengths and standard deviation were calculated for all
the samples.
B. Pellets Properties
[0207] Table 1 below shows the Drop Number of BHD pellets. All the
green pellets were optimized to demonstrate a Drop Number of more
than 4. A minimum of 3 drops are required for pellets to be
transported for sintering in a commercial pelletizing/sintering
plant.
TABLE-US-00002 TABLE 1 Typical drop number of BHD green EAFD
pellets with varying contents of moisture and binder after
optimizing drop number Mois- Average ture Binder, Drop Sample
weight weight Test Test Test Test Test Number No % % 1 2 3 4 5
Score 1 8 2.00 6 6 5 4 5 5.2 2 9 2.00 9 9 10 10 12 10 3 10 2.00 7 8
8 7 9 7.8 4 8 1.50 6 8 5 7 6 6.4 5 9 1.50 6 7 7 5 6 6.2 6 10 1.50 3
4 4 5 6 4.2 7 11 1.25 3 4 4 3 5 3.8 8 10 1.25 3 3 4 5 6 4.2 9 9
1.25 5 7 4 4 4 4.8 10 8 1.25 6 7 6 6 5 6
[0208] The pellets were dried in the sun only. No heating was used
for strength enhancement. Table 2 below shows the compressive
strength of dried BHD pellets. All the dried pellets were optimized
to demonstrate Compressive Strength in the range of 40-108 kg per
pellet. This was measured using Instron Compression strength
testing machine.
TABLE-US-00003 TABLE 2 Typical Compressive of Strength of Dried
Pellets after Optimizing the Binder Proportion Pellet Number
Compressive Strength, kgf/Pellet 1 82 2 42 3 89 4 78 5 56 6 41 7 48
8 108 9 52
2. Example 2
Heating and Separation of Zinc by Evaporization
[0209] The heating/sintering of BHD pellets and evaporization of
volatiles was conducted in a Static Reduction Reactor.
[0210] The specific conditions involved in the sintering test were:
heating to the desired temperature in the desired gas atmosphere;
sintering in a fixed bed; and sintering by means of inert gases and
a sample having a size range of 12 mm-16 mm. The current study was
conducted according to the BS6598-1985 corresponding to ISO
4695-1984 (used for evaluating iron ore reducibility) with some
deviations modification to correlate the test requirements.
Non-isothermal sintering was used. Instead of a mixture of carbon
monoxide and nitrogen, an inert gas was used.
[0211] The apparatus consisted of a reduction furnace supplied by
Labomatic fitted with the following provisions:
I. A system to supply and regulate the gases II. A reduction tube
of heat resistant steel III. A weighing device to determine the
oxygen loss at regular intervals IV. An electrically heated furnace
to heat the test portion to the specified temperature V. A chart
recorder and control panel
[0212] The sintering tube was made of non-scaling, heat resistance
metal to withstand temperatures of higher than 1100.degree. C. The
wire grid was mounted in the reduction tube at the quarter depth
from the bottom of the retort, for supporting the raw material test
portion. The weight of the sample used for each sintering test was
500 g.+-.2 g. The weighing device with this equipment was capable
of weighing the load to an accuracy of 1 g. The weighing device was
checked for sensitivity at regular intervals.
[0213] Each sample containing 500 g of dried BHD pellets was then
heated at 700-1100.degree. C. in an atmosphere of N.sub.2, to study
the effects of this inert gas on zinc removal. The samples were
heated until there is no more loss of weight. The samples were left
in the furnace to cool down to room temperature. The residual
pellets and vapor condensates were analyzed for chemical
composition using XRF, C & S Analyzers and phases using XRD
techniques.
3. Example 3
Sintering of BHD Pellets in N.sub.2 Atmosphere
[0214] The samples were sintered in a furnace under a N.sub.2
atmosphere at different temperatures. The weight of the sample
before sintering was 500.+-.2 g. The weight of the sample was taken
after the sintering as well. FIG. 2 shows the weight loss of BHD
pellets in N.sub.2 atmosphere at different temperatures.
[0215] FIG. 3 shows the comparison of Zn content of BHD pellets
sintered in N.sub.2 atmosphere at various temperatures.
[0216] FIG. 4 is a graph depicting the Zn and Pb content of pellets
sintered under a nitrogen atmosphere at various temperatures.
[0217] FIG. 5 gives the Zn and Pb content of vapor condensate
extracted from BHD pellets by sintering in nitrogen at various
temperatures.
[0218] FIG. 6 gives the weight % of Zn removed from BHD pellets
during sintering in a N.sub.2 atmosphere at different temperatures.
The values were summarized in Table 3 below. As shown, 85% and 97%
of the Zn could be removed from BHD at temperatures 1000.degree. C.
and 1100.degree. C. in a N.sub.2 atmosphere, respectively. However,
oxygen in iron oxide could not be removed with N.sub.2. Hence, the
residue comprises iron in the form of iron oxide. The chemical
analysis of the vapor condensate showed that the total zinc content
was in the form of metallic Zn and ZnO, and it was mixed with PbO,
Na, K, and Cl. Further hydrometallurgical treatment was required to
separate all these constituents.
TABLE-US-00004 TABLE 3 Zn content and percentage of Zn removed from
BHD pellets Entry Zn Content in BHD % Zn No. T (.degree. C.) Pellet
(wt %) Removed 1 Room 15.39 (Before sintering) 0 temperature 2 900
14.12 (After sintering) 8.3 3 950 3.85 (After sintering) 75 4 1000
2.20 (After sintering) 85.7 5 1050 1.28 (After sintering) 91.7 6
1100 0.37 (After sintering) 97.6
[0219] The comparison of the weight loss of other elements is shown
in FIG. 7. The elements Pb, K, Na and Cl were removed at
temperatures starting at about 900.degree. C. The analysis of the
vapor condensate indicated that Zn occurred in the form of
elemental Zn and ZnO and it was mixed with PbO, Na, K and Cl. Table
4 summarizes the composition of the elements found in the
condensate upon sintering at 1000.degree. C. Further
hydrometallurgical treatment was required to separate all these
constituents.
TABLE-US-00005 TABLE 4 Chemical Composition of Pellets and Vapor
Condensate produced in N.sub.2 atmosphere at 1000.degree. C.
Compound Pellet Concentration (wt %) Condensate Concentration MgO
1.42 Trace Al.sub.2O.sub.2 0.648 Trace SiO.sub.2 4.72 0.0056
P.sub.2O.sub.5 0.324 0.22 S 0.187 0.101 CI 0.0757 6.7 K.sub.2O
0.715 13.87 CaO 18.13 0.18 TiO.sub.2 0.0923 0.014 MnO 1.272 0.01 Ni
0.0475 0.0296 Cu 0.0476 0.248 ZnO 5.125 66.7568 Cd Trace 0.046 Sn
0.0082 0.022 PbO 0.146 11.53 Fe.sub.2O.sub.3 66.8949 0.25
[0220] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the scope or spirit of the invention. Other
embodiments of the invention will be apparent to those skilled in
the art from consideration of the specification and practice of the
invention disclosed herein. It is intended that the specification
and examples be considered as exemplary only, with a true scope and
spirit of the invention being indicated by the following
claims.
* * * * *