Method and arrangement for recovering metal from waste slag

Abstract

NOT VISIBLE DUE TO STATUS OF PATENT

Description

[0001] METHOD AND ARRANGEMENT FOR RECOVERING METAL FROMWASTE SLAG BACKGROUND The invention relates to a method for recovering metal from waste slag.The invention further relates to an arrangement for recov-ering metal from waste slag.E-waste slag is formed during smelting of E-waste that com-prises e.g. electronic scrap and circuit boards. Due to theimpurities in the slag, it is difficult to find a directuse of the slag, for example as construction material. Dueto the highly reducing environment when smelting E-waste, the properties of the E-waste slag differ from the typical primary copper smelter slag. The recovery loss of copper and other metals when smelting E-waste is mainly due to physical inclusions of metallic droplets in the E-wasteslag. Due to the high viscosity of the E-waste slag, apyrometallurgical settling furnace is not ideal for sepa-rating the metal from the rest of the E-slag. Solidificationand crushing the E-slag is also not ideal solution due toa long process lead time, high equipment costs and higherenergy consumption. BRIEF DESCRIPTIONViewed from a first aspect, there can be provided a methodfor recovering metal from waste slag, the method comprising:- receiving slag in at least partly molten state,- granulating said slag in said at least partly moltenstate,- allowing granulated slag to solidify,- separating said granulated slag into at least two frac-tions such that- in a first of said at least two fractions metal contentis higher as in a second of said at least two fractions.Thereby a method having a short process lead time and lowenergy consumption, but still achieving the same processresults as the known methods may be achieved. Additionally,the method is more environmentally friendly as it does notproduce any direct CO2 emissions and indirect CO2 emissionsare lower than in alternative solutions. Viewed from a further aspect, there can be provided an arrangement for recovering metal from waste slag, the ar-rangement comprising a granulating arrangement arranged forreceiving slag in at least partly molten state and granu- lating said slag in said at least partly molten state, anda first separation unit arranged for separating said gran-ulated slag into at least two fractions, wherein in a firstof said at least two fractions metal content is higher asin a second of said at least two fractions.Thereby an arrangement providing a short process lead timeand low energy consumption, but still achieving the sameprocess results as the known arrangements may be achieved.Additionally, the arrangement necessitates low capital ex- penditures and is environmentally friendly as it does not produce any direct CO2emissions.The arrangement and the method are characterised by what isstated in the independent claims. Some other embodimentsare characterised by what is stated in the other claims. Inventive embodiments are also disclosed in the specifica-tion and drawings of this patent application. The inventivecontent of the patent application may also be defined inother ways than defined in the following claims. The in-ventive content may also be formed of several separate in- ventions, especially if the invention is examined in the light of expressed or implicit sub-tasks or in view ofobtained benefits or benefit groups. Some of the definitionscontained in the following claims may then be unnecessaryin view of the separate inventive ideas. Features of thedifferent embodiments of the invention may, within the scopeof the basic inventive idea, be applied to other embodi-ments. Various embodiments of the first aspect may comprise at least one feature from the following paragraphs:In one embodiment, the method comprises receiving slag froma furnace, such as a top blown rotary converter.An advantage is that the slag has a high temperature andits premature solidifying may be avoided.In one embodiment, the method comprises discharging slagfrom the furnace in a vessel and discharging said slag from the vessel for granulating said slag. An advantage is that some flexibility in the layout of the arrangement may be achieved.In one embodiment, at least part of slag originates from atleast one source selected from electronic scrap, cable scrap, plastic scrap from electrical or electronic devices, incinerator bottom ash, copper scrap, and Cu alloys.An advantage is that these sources typically include valu-able metals that are worth of recycling.In one embodiment, granulating comprises blowing fluid intoa stream of slag being in at least partly molten state, such that granules are created.An advantage is that a quick granulation and cooling of theslag may be achieved.In one embodiment, the granulating comprises blowing steamor gas, such as air.An advantage is that produced granules are at least essen-tially dry.In one embodiment, the granulating comprises blowing liq-uid, such as water.An advantage is that granules may be effectively cooled andsolidified.In one embodiment, the separation comprises a magnetic sep-aration phase.An advantage is that a separation phase having low energyconsumption and without producing any direct CO2emissions may be achieved.In one embodiment, the magnetic separation phase is per-formed by a low intensity magnetic separator.An advantage is that a low maintenance need and operatorattendance may be achieved.In one embodiment, the separation comprises a gravimetricseparation phase.An advantage is that an operation having low cost, requiringa simple apparatus and being environmentally friendly maybe achieved.In one embodiment, the first fraction contains metal 10weight-% to 90 weight-%.An advantage is that a cost-effective the separation phaseand the method may be achieved.In one embodiment, said metal comprises at least one ofcopper, silver, gold, palladium, platina.An advantage is that a cost-effective the separation phaseand the method may be achieved.In one embodiment, said metal is in a mixture called blackcopper that is attracted to magnets.An advantage is that non-magnetic metals, such as copper,included in black copper may be separated by a magneticseparation phase.In one embodiment, the method comprises grinding the secondfraction and providing thus a grinded second fraction, per- forming a separation phase of the grinded second fraction into at least two grinded fractions such that in a first of said at least two grinded fractions metal content is higher as in a second of said at least two grinded fractions.An advantage is that metal(s) in the reject of the separa-tion phase may still be separated from the slag.In one embodiment, the separation phase of the grinded sec-ond fraction comprises a gravimetric separation of saidgrinded second fraction into a first sub-fraction and asecond sub-fraction.An advantage is that an operation having low cost, requiringa simple apparatus and being environmentally friendly may be achieved.In one embodiment, the method comprises performing a furtherseparation of the first grinded fraction by a flotation method.An advantage is that metal(s) in the reject of the separa-tion phase may still be separated from the slag.In one embodiment, the arrangement comprises a grindingarrangement arranged for grinding the second fraction andproviding a grinded second fraction, a second separationunit arranged for performing a separation phase of the grinded second fraction into at least two grinded sub-frac- tions such that in a first of said at least two grinded sub- fractions metal content is higher as in a second of said at least two grinded sub-fractions. An advantage is that metal(s) in the reject of the separa- tion phase may still be separated from the slag.In one embodiment, the second separation unit comprises agravimetric separation apparatus.An advantage is that a second separation unit having lowcost, requiring a simple apparatus and being environmentally friendly may be achieved.In one embodiment, the second separation unit comprises amagnetic separation apparatus.An advantage is that a second separation unit having low energy consumption and without producing any direct CO2emissions may be achieved.In one embodiment, the arrangement comprises a flotationarrangement arranged for performing a further separation of the second grinded sub-fraction.An advantage is that the separation capacity of the ar-rangement may be further raised. Based on the above mentioned, it should be noted that dif- ferent embodiments mentioned in the above paragraphs may combined in any possible suitable manner for implementing the present invention. BRIEF DESCRIPTION OF FIGURESSome embodiments illustrating the present disclosure aredescribed in more detail in the attached drawing, in which: Figure 1 is a schematic view of a method and an arrangement for recovering metal from waste slag in partial cross-sec- tion,Figure 2 is a schematic side view of a separation unit usedin a method and an arrangement for recovering metal from waste slag in partial cross-section, andFigures 3a – 3c are schematic side views of other separationunits used in a method and an arrangement for recoveringmetal from waste slag. In the figure, some embodiments are shown simplified forthe sake of clarity. Similar parts are marked with the samereference numbers in the figures. DETAILED DESCRIPTIONFigure 1 is a schematic view of a method and an arrangementfor recovering metal from waste slag in partial cross-sec-tion, Figure 2 is a schematic side view of a separation unit used in a method and an arrangement for recovering metalfrom waste slag in partial cross-section, and Figures 3a -3c are schematic side views of other separation units usedin a method and an arrangement for recovering metal from waste slag. The method is run in an arrangement 100 the main parts or components of which comprise a granulating arrangement 3and a first separation unit 4.The method and the arrangement 100 are controlled througha control unit 14, which may be a computer, a computationunit or a device comprising at least one processor and a memory.In one embodiment, the granulating arrangement 3 is arrangedfor receiving slag directly from a furnace 1 in which saidslag has been melted.In one embodiment, such as shown in Figure 1, slag is firsttapped into a vessel 15, such as a ladle, and then, ifrequired, moved M to a place where slag is poured from thevessel 15 into the granulating arrangement 3.In one embodiment, the slag originates from recycled waste,such as recycled electronic waste. In one embodiment, atleast part of the slag originates from at least one source selected from electronic scrap, cable scrap, plastic scrap from electrical or electronic devices, incinerator bottomash, copper scrap, such as copper pipes used in constructionindustry, and Cu alloys. Typically, the recycled waste isa combination of wastes originating from different sources.In one embodiment, the furnace 1 is a top blown rotaryconverter, such as a Kaldo converter. The top blown rotaryconverter is shaped like an open-ended barrel and inside lined with refractory material. The top blown rotary con- verter can be rotated about its longitudinal axis X and tilted T about an axis perpendicular to said longitudinalaxis X. The slag molten in the top blown rotary converteris discharged through a mouth 2 by tilting.In one embodiment, the furnace 1 is an Isasmelt furnace. Inone embodiment, the furnace 1 is an Ausmelt furnace.In one embodiment, the method is run and the apparatus used batch-wise so that molten slag discharged from the furnace1 is processed as a batch. In another embodiment, the methodis run and the apparatus used in a continuous way.In one embodiment, preceding or following discharging slagfrom the furnace 1, there is a metal discharging step wherea melted metal phase is discharged from the furnace 1 intoanother arrangement (not shown) for further processing.The granulating arrangement 3 receives and granulates slagthat is at least partly in molten. The slag may include solid (not melted) particles or fragments in addition to flowable (melted) phase. The granulating arrangement 3 com- prises means for pressurizing fluid that is then blown through blowing means into a stream of slag S that is in atleast partly molten state. In one embodiment, the blowingmeans comprises openings or nozzles 17 that are arranged ina blowing box 16, for instance. Fluid F is blown throughsaid openings or nozzles with high speed into the stream ofslag S that is in at least partly molten state. In oneembodiment, the fluid F is blowed in the stream of slag S that is being poured or discharged from the furnace 1. In one embodiment, the fluid F is blowed in the stream of slag S that is being poured or discharged from a vessel, such as the ladle 15.In one embodiment, the stream of slag S is fed in or on arunner 8 that is arranged to direct said slag in the gran- ulating arrangement 3. In one embodiment, granulation of the slag takes place in a granulation pit 9 provided in the granulating arrangement 3. In one embodiment, the bottom of the granulation pit 9 is at least partly filled with liquid, such as water, and the granules enter and cool down in said liquid.In one embodiment, the fluid F is blowed at least mainly inhorizontal direction and the stream of slag S is configuredto drop through said fluid. It is to be noted, however, thatother arrangements of the fluid F and the stream of slag Smay be used in granulation of the slag.In one embodiment, the fluid F comprises steam or gas, suchas air. In one embodiment, the fluid F comprises liquid,such as water. In one embodiment, the fluid F provides ahigh pressure turbulent liquid stream. The characterizing features of the fluid F, such as its velocity, temperature and volume flow, are selected depending on e.g. the char- acteristics of the molten slag and the flow thereof.In one embodiment, the granulating arrangement 3 comprisesa centrifugal granulating apparatus. In this apparatus thestream of slag is poured on a disc that is spinning at highspeed. Forces caused by the spinning breaks the slag intogranules. In one embodiment, the spinning disc throws thegranules in air where they cool down and solidify. In an-other embodiment, the spinning disc throws the granules inin liquid such as water, where they cool down and solidify. As the slag is being granulated, it also cools so that solidsmall pieces or droplets are produced. Some heat is removedfrom the slag by evaporation of liquid (typically water)and / or as heated gas (typically air) and / or liquid. In watergranulation, it is possible to use an abundance of water that may then reused and pumped back in the granulation process.In one embodiment, the granulating arrangement 3 producesgranules having mean size in range of 0,5 mm to 5 mm. It is to be noted, however, that the size distribution of the granules may be varied, for instance from few microns to over 5 mm. The granules G, i.e. granulated slag, are delivered to afirst separation unit 4. In one embodiment, there may be adrying step and a drying apparatus where the granules aredried prior to their feeding in the first separation unit4. However, the drying step and the drying apparatus arepreferably avoided. If the separation step carried out in the first separation unit requires dry material, the gran-ulation step preferably uses dry granulation without anyliquid.The first separation unit 4 separates said granules G intoat least two fractions. In one embodiment, such as shown inFigure 1, the first separation unit 4 separates the granulesG into two fractions, i.e. into a first fraction A and asecond fraction B such that the first fraction A has ahigher metal content as the second fraction B.In one embodiment, the first fraction A contains metal 10weight-% to 90 weight-%. In one embodiment, the first frac-tion A contains metal 30 weight-% to 70 weight-%.In one embodiment, the metal comprises at least one ofcopper, silver, gold, palladium, platina. In one embodiment,the metal is a mixture comprising copper and ferrous andnon-ferrous metals, typically including silver, gold,palladium, platina, so called black copper. Black coppercomprises metallic iron, which renders the black copper phase magnetic.In one embodiment, the first separation unit 4 comprises amagnetic separation apparatus and the separation comprisesa magnetic separation phase. One embodiment of the magneticseparation apparatus 12 is shown in Figure 2. In one embod-iment, the magnetic separation apparatus 12 is a low inten-sity magnetic separator.The low intensity magnetic separator (LIMS) is a device thatis used to recover magnetic material from non-magnetic ma- terial, or more magnetic material from less magnetic mate-rial. In one embodiment, the magnetic separation apparatus12 is designed to work with dry separation process. Inanother embodiment, the magnetic separation apparatus 12 isdesigned to work with wet separation process.In one embodiment, the magnetic separation apparatus 12comprises a separator drum 10 that rotates R around itsvertically arranged axis. A magnet arrangement 11 is ar-ranged inside the separator drum 10. The magnet arrangement 11 extends only on a part of the length of the circumference of the separator drum. The magnetic or more magnetic mate- rial is attracted to the separator drum 10 by the magnetarrangement 11 and is rotated out of the non-magnetic orless magnetic particle stream on the surface of the drum.In one embodiment, the magnetic or more magnetic materialdetach from the separator drum 10 upon reaching a specific boundary point, such as a baffle, and fall into e.g. acollection container. In one embodiment, the magnetic ma-terial discharges from the separator drum when it is rotatedout of the magnetic field. Thus, the granules G are sepa-rated to the first fraction A and the second fraction Bbased on magnetic properties thereof. It is to be noted,however, that the magnetic separation apparatus 12 may beconstructed in many alternative ways.In one embodiment, the first separation unit 4 comprises agravimetric separation apparatus 13 and the separation agravimetric separation phase. One embodiment of the gravi-metric separation apparatus 13 is shown in Figure 3a. Theworking principle of this separation apparatus 13 is basedon a centrifugal separation, that means separating sub-stances with different specific gravities by means of cen-trifugal force. Thus, the granules G are separated to thefirst fraction A and the second fraction B based on theirspecific gravities. It is to be noted, however, that thegravimetric separation apparatus 13 may be constructed inmany alternative ways. Another embodiment of the gravimet-ric separation apparatus 13 is shown in Figure 3b. Thisapparatus 13 is a scavenging spiral where separation ofdifferent solid materials or components in slurry is based on solid particle density and particle’s hydrodynamic prop-erties. Still another embodiment of the gravimetric sepa-ration apparatus 13 is a shaking table or gravity separationtable, such as shown in Figure 3c. In this apparatus rela-tive movements against gravitational forces are applied to the particles.The first fraction A provided by the separation phase thatis carried out by the first separation unit 4 has a highmetal content and it can be transported out from the methodand the arrangement 100 to be utilized in any suitable use.In one embodiment, the second fraction B provided by theseparation phase and having a low metal content may beconsidered as waste. In another embodiment, the second frac-tion B is further processed for further recovery of metal(s)still in the second fraction.In one embodiment, the second fraction B, i.e. granuleshaving low metal content, is grinded into a grinded secondfraction, and this grinded second fraction BG is then sep-arated into at least two grinded fractions.The second fraction B is grinded by a grinding arrangement5 that comprises a suitable grinding or crushing machine.The type of said grinding or crushing machine may be e.g.a jaw crusher, a gyratory crusher, a cone crusher, a ballmill, a rod mill or an impact crusher.In one embodiment, the grinding arrangement 5 is followedby a second separation unit 6 where the grinded secondfraction BG is separated into at least two grinded frac-tions. In one embodiment, the grinded second fraction BG isseparated into a first grinded fraction BG1 and a secondgrinded fraction BG2. The metal content of the first grindedfraction BG1 is higher than of the second grinded fractionBG2. In one embodiment, the second separation unit 6 com-prises a magnetic separation apparatus 12. In one embodi-ment, the second separation unit 6 comprises a gravimetricseparation apparatus 13. The same principles of the magneticseparation apparatuses and the gravimetric separation ap-paratuses described already in connection with the firstseparation unit apply also here in the second separationunit 6.The first grinded fraction BG1 can be transported out fromthe method and the arrangement 100 to be utilized in any suitable use. In one embodiment of the method and the arrangement, thesecond grinded fraction BG2 , i.e. the grinded fractionhaving a lower metal content, is fed in a flotation ar-rangement 7 for carrying out a further refining of thefraction. The flotation arrangement 7 separates the grinded fraction BG2 into two fractions such that one of said two fractions has a higher metal content than another of said two fractions. The invention is not limited solely to the embodiments de- scribed above, but instead many variations are possible within the scope of the inventive concept defined by the claims below. Within the scope of the inventive concept the attributes of different embodiments and applications can be used in conjunction with or replace the attributes of an- other embodiment or application. The drawings and the related description are only intendedto illustrate the idea of the invention. The invention mayvary in detail within the scope of the inventive idea de- fined in the following claims.

[0002] REFERENCE SYMBOLS1 furnace2 mouth3 granulating arrangement4 first separation unit5 grinding arrangement6 second separation unit7 flotation arrangement8 runner9 granulation pit10 separator drum11 magnet arrangement12 magnetic separation apparatus13 gravimetric separation apparatus14 control unit15 vessel16 blowing box17 opening100 arrangementA first fractionB second fractionBG grinded second fractionBG1 first sub-fraction of grinded second fractionBG2 second sub-fraction of grinded second fractionF fluidG granulesM movingR rotationS slag flowT tilting

Claims

CLAIMS 1. A method for recovering metal from waste slag, the method comprising:- receiving slag in at least partly molten state,- granulating said slag in said at least partly moltenstate,- allowing granulated slag to solidify,- separating said granulated slag into at least two frac-tions such that- in a first of said at least two fractions metal contentis higher as in a second of said at least two fractions.

2. The method as claimed in claim 1, comprising- receiving slag from a furnace (1).

3. The method as claimed in claim 2, comprising- receiving slag from a top blown rotary converter.

4. The method as claimed in claim 2 or 3, comprising- discharging slag from the furnace in a vessel (15), and- discharging from the vessel for granulating said slag.

5. The method as claimed in any of the preceding claims, wherein at least part of slag originates from at least one source selected from- electronic scrap,- cable scrap,- plastic scrap from electrical or electronic devices,- incinerator bottom ash,- copper scrap, and- Cu alloys.

6. The method as claimed in any of the preceding claims, wherein- said granulating comprises blowing fluid into a stream ofslag being in at least partly molten state, such that- granules are created.

7. The method as claimed in claim 6, wherein- blowing fluid comprises blowing steam or gas, such as air.

8. The method as claimed in claim 6 or 7, wherein- blowing fluid comprises blowing liquid, such as water.

9. The method as claimed in any of the preceding claims, wherein- the separation comprises a magnetic separation phase.

10. The method as claimed in any of the preceding claims, wherein- the separation comprises a gravimetric separation phase.

11. The method as claimed in any of the preceding claims, wherein- the first fraction contains metal 10 weight-% to 90weight-%.

12. The method as claimed in any of the preceding claims, wherein- said metal comprises at least one of copper, silver, gold,palladium, platina.

13. The method as claimed in any of the preceding claims, wherein- said metal is in a mixture called black copper.

14. The method as claimed in any of the preceding claims, comprising- grinding the second fraction and providing thus a grindedsecond fraction.

15. The method as claimed in claim 14, comprising- performing a separation phase of the grinded second frac-tion into at least two grinded sub-fractions such that- in a first of said at least two grinded sub-fractionsmetal content is higher as in a second of said at least two grinded sub-fractions.

16. The method as claimed in claim 15, wherein- the separation phase of the grinded second fraction com-prises a gravimetric separation.

17. The method as claimed in claim 15, wherein- the separation phase of the grinded second fraction com-prises a magnetic separation.

18. The method as claimed in claim 16 or 17, comprising- performing a further separation of the first grinded sub-fraction by a flotation method.

19. An arrangement for recovering metal from waste slag, the arrangement (100) comprising- a granulating arrangement (3) arranged for receiving slagin at least partly molten state and granulating said slagin said at least partly molten state, and- a first separation unit (4) arranged for separating saidgranulated slag into at least two fractions, wherein in a first (A) of said at least two fractions metal content is higher as in a second (B) of said at least two fractions.

20. The arrangement as claimed in claim 19, comprising- a vessel (15) arranged for keeping slag in at least partlymolten state, and for- discharging said slag in the first separation unit (4).

21. The arrangement as claimed in claim 19 or 20, whereinat least part of slag originates from at least one source selected from- electronic scrap,- cable scrap,- plastic scrap from electrical or electronic devices,- incinerator bottom ash,- copper scrap, and- Cu alloys.

22. The arrangement as claimed in any of claims 19-21,wherein- the granulating arrangement (3) is configured to blowfluid (F) into a stream of slag being in at least partly molten state.

23. The arrangement as claimed in claim 22, wherein- the fluid (F) comprises steam or gas, such as air.

24. The arrangement as claimed in claim 22 or 23, wherein- the fluid (F) comprises liquid, such as water.

25. The arrangement as claimed in any of claims 19-24, wherein- the first separation unit (4) comprises a magnetic sepa-ration apparatus.

26. The arrangement as claimed in any of claims 19-24,wherein- the first separation unit (4) comprises a gravimetricseparation apparatus.

27. The arrangement as claimed in any of claims 19-26,wherein- said metal comprises at least one of copper, silver, gold,palladium, platina.

28. The arrangement as claimed in any of claims 19-27,wherein- said metal is in a mixture called black copper.

29. The arrangement as claimed in any of claims 19-28,comprising- a grinding arrangement (5) arranged for grinding the sec-ond fraction (B) and providing a grinded second fraction30. The arrangement as claimed in claim 29, comprising- a second separation unit (6) arranged for performing aseparation phase of the grinded second fraction (BG) into at least two grinded sub-fractions such that- in a first (BG1) of said at least two grinded sub-frac-tions metal content is higher as in a second (BG2) of saidat least two grinded sub-fractions.

31. The arrangement as claimed in claim 30, wherein- the second separation unit (6) comprises a second gravi-metric separation apparatus.

32. The arrangement as claimed in claim 30, wherein- the second separation unit (6) comprises a second magneticseparation apparatus.

33. The arrangement as claimed in any of claims 29 - 321,comprising- a flotation arrangement (7) arranged for performing afurther separation of the second (BG2) grinded sub-fraction.