WO2025186502A1

WO2025186502A1 - Method for recovering metal and arrangement

Info

Publication number: WO2025186502A1
Application number: PCT/FI2024/050096
Authority: WO
Inventors: Changji XUAN; Mathias STENLUND
Original assignee: Metso Metals Oy
Current assignee: Metso Metals Oy
Priority date: 2024-03-07
Filing date: 2024-03-07
Publication date: 2025-09-12
Anticipated expiration: 2026-09-07
Also published as: WO2025186502A8

Abstract

A method and an arrangement for recovering metal from recycled materials comprising organic substances, the method comprising: - feeding a recycled material (20) into a furnace (1) until a predetermined batch quantity is reached, - implementing a melting stage (21) comprising a semi-combustion step (22) followed by a melting step (23), - discharging melted slag and feeding it to a slag cleaning process (24), wherein - following the melting stage, implementing a converting stage (25) for converting remaining material into a refining slag and a raw copper, - discharging the refining slag (26) from the furnace (1), and - discharging the raw copper (27) from the furnace (1) into a further Cu processing stage.

Description

METHOD FOR RECOVERING METAL AND ARRANGEMENT

BACKGROUND

The invention relates to a method for recovering metal from recycled materials comprising organic substances .

The invention further relates to an arrangement for recovering metal from recycled materials comprising organic substances .

The recycling of scrap materials plays a vital role in resource conservation and the establishment of a sustainable economy . The rapid advancement of technology and the economy has led to a substantial increase in the production of various material s containing significant amounts of organic substances . Consequently, there has been a significant rise in the volume of related scrap materials in recent decades . For example consumer electronic devices have relatively short service lives due to factors like frequent innovations in new products and rapid changes in equipment features . As a result , global e-waste production has experienced substantial growth and is expected to continue increasing in the near future . These scrap materials , such as e-waste , copper scrap with insulation cables , and lead scrap from batteries , comprise a complex mixture of high-value metals (e . g . , Cu, Pb, Sn, Au, Ag, etc . ) , plastics , and hazardous components . The high levels of organic constituents in these materials ' present significant challenges for recycling due to the substantial energy generation and the emis sion of hazardous substances during the process of expelling organics .

BRIEF DESCRIPTION

Viewed from a first aspect , there can be provided a method for recovering metal from recycled materials comprising organic substances , the method comprising : - feeding continuously a main recycled material , comprising said organic substances , into a furnace until a predetermined batch quantity is reached,

- implementing a melting stage comprising a semi-combustion step followed by a melting step, wherein

- in said semi-combustion step a sufficient temperature for combusting organic substances but below the melting temperature of said metal is maintained, combusting said organic substances and generating a reducing atmosphere , preventing the undesired oxidation of the metal in the furnace , and

- in said melting step following combustion of said organic substances , raising the temperature to or over melting temperature of said metal , and

- discharging melted slag and feeding it to a slag cleaning process , wherein

- following the melting stage , implementing a converting stage for converting remaining material into a refining slag and a raw copper,

- discharging the refining slag from the furnace , and

- discharging the raw copper from the furnace into a further Cu processing stage .

Thereby many advantages may be achieved . The implementation of continuous feeding results in a more uniform and stable reaction condition compared to conventional batch-wise feeding methods . The recovery yield of the recycled material maybe significantly increased, and high-purity products such as raw copper and Pb-Sn alloy may be produced . Still further, all the byproducts are efficiently returned to the process system to minimi ze losses .

Viewed from a further aspect , there can be provided an arrangement for carrying out the method of the first aspect .

The method and the arrangement are characterised by what is stated in the independent claims . Some other embodiments are characterised by what is stated in the other claims . Inventive embodiments are also di sclosed in the specification and drawings of this patent application . The inventive content of the patent application may also be defined in other ways than defined in the following claims . The inventive content may also be formed of several separate inventions , especially if the invention is examined in the light of expressed or implicit sub-tasks or in view of obtained benefits or benefit groups . Some of the definitions contained in the following claims may then be unnecessary in view of the separate inventive ideas . Features of the different embodiments of the invention may, within the scope of the basic inventive idea, be applied to other embodiments .

Various embodiments of the first aspect may comprise at least one feature from the following paragraphs :

In one embodiment , the melting stage comprises at least two semi-combustion steps , each followed by the melting step, and the method comprises

- discharging a smelting slag created in the melting step prior to the following semi-combustion step .

In one embodiment , the melting stage comprises a first semicombustion step, a first melting step, a second semi combustion step as the last of the semi-combustion steps , and a second melting step as the last of the melting steps .

In one embodiment , the method comprises feeding continuously the main recycled material in at least two semi-combustion steps .

In one embodiment , the method comprises feeding the main recycled material in all the semi-combustion steps .

In one embodiment , the method comprises feeding a batch of coarse material in at least one semi-combustion step .

In one embodiment , the main recycled material comprises electronic scrap , cable scrap, plastic scrap from electrical or electronic devices , insulation or isolation materials , or any combinations thereof .

In one embodiment , said converting stage comprises at least two converting steps , wherein following the first of said converting steps , discharging ref ining slag and continuing converting remaining refined black copper in a next converting step, discharging secondary oxidation slag from said next converting step back to the first of said converting steps and discharging the raw copper from the last of said at least two converting steps into the further Cu processing stage .

In one embodiment , the method comprises adding copper scrap and/or slag forming fluxes in the converting stage .

In one embodiment , the method comprises converting the black copper into a refined black copper by adding therein Cu-Ni alloy . In one embodiment , the method comprises granulating the slag received from the melting stage into a granulated slag, and separating the granulated slag to a metal rich phase and a discarded slag .

In one embodiment , the method comprises separating the granulated slag by using a magnetic separation method .

In one embodiment , the method comprises feeding the metal rich phase in the melting step of a following batch .

In one embodiment , the method comprises allowing the slag to settle prior to its granulation, such that a black copper phase and a settled slag phase are separated, and granulating said settled slag phase .

In one embodiment , the method comprises feeding the black copper phase back in the converting stage for converting into a refined black copper .

In one embodiment , the method comprises running the melting stage and the converting stage in a same furnace .

In one embodiment , the method comprises running the melting stage and the converting stage in separate furnaces by running the melting stage in a melting furnace , feeding the black copper from the melting furnace in a separate refining furnace , and running the converting stage in said refining furnace .

In one embodiment , the method comprises discharging raw copper from the converting stage into an anode furnace , and processing said raw copper into a refined anode copper .

In one embodiment , the method comprises adding copper scrap in said raw copper in the anode furnace . In one embodiment , the method comprises discharging anode slag from the anode furnace , and feeding said anode slag in the melting stage of a following batch .

In one embodiment , the method comprises recovering the refining slag originating from the converting stage in a separate slag recovery furnace , wherein said recovering comprises adding to the refining slag a reduction agent and converting the refining slag into Pb-Sn slag and Cu-Ni alloy, discharging said Cu-Ni alloy from the slag recovery furnace , continuing recovering said Pb-Sn slag in a further reduction step by adding a reduction agent therein for producing a crude Pb-Sn alloy, mixing the crude Pb-Sn with silicon containing material and melting composition thus created, and mixing said composition for producing a refined Pb-Sn alloy and silicate dross .

In one embodiment , the method comprises feeding said Cu-Ni alloy into the converting stage of a following batch .

In one embodiment , the method comprises feeding the silicate dross in the converting stage of a following batch .

In one embodiment , the method comprises mixing the crude Pb-Sn with silicon containing material and melting composition thus created in a ladle .

In one embodiment , the method comprises processing the composition of the crude Pb-Sn and the silicon containing material in molten state in a drossing unit , maintaining a protective atmosphere in the drossing unit , cooling the composition in the drossing unit gradually, precipitating silicate inclusions from the composition during said cooling, and allowing said silicate inclusions to coagulate and form silicate dross on the surface of the melt . In one embodiment , the method comprises skimming said silicate dross from the drossing unit .

In one embodiment , the method comprises discharging a refined Pb-Sn alloy from the drossing unit .

In one embodiment , the method comprises discharging a silicate dross from the drossing unit , and feeding said silicate dross in the converting stage of a following batch .

In one embodiment , the furnace is a ti ltable and rotatable top blown rotary converter .

Based on the above mentioned, it should be noted that different embodiments mentioned in the above paragraphs may combined in any possible suitable manner for implementing the present invention .

BRIEF DESCRIPTION OF FIGURES

Some embodiments illustrating the present disclosure are described in more detail in the attached drawings , in which

Figure 1 illustrates a method and an arrangement for recovering metal from recycled materials comprising organic substances ,

Figure 2 illustrates another method and arrangement for recovering metal from recycled materials comprising organic substances ,

Figure 3 is a schematic view of a step of a method for recovering metal from recycled materials comprising organic substances in partial cross-section, Figure 4 is a schematic view of another step of a method for recovering metal from recycled materials comprising organic substances in partial cross-section,

Figure 5 illustrates a stage of a method for recovering metal from recycled materials comprising organic substances ,

Figure 6 illustrates another stage of a method for recovering metal from recycled materials comprising organic substances ,

Figure 7 is a schematic view of a third step of a method for recovering metal from recycled materials comprising organic substances in partial cross-section,

Figure 8 illustrates a third stage of a method for recovering metal from recycled materials comprising organic substances ,

Figure 9 is a schematic view of a fourth step of a method for recovering metal from recycled materials comprising organic substances in partial cross-section, and

Figure 10 illustrates a fourth stage of a method for recovering metal from recycled materials comprising organic substances .

In the figures , some embodiments are shown simplified for the sake of clarity . Similar parts are marked with the same reference numbers in the figures .

DETAILED DESCRIPTION

Figure 1 illustrates a method and an arrangement for recovering metal from recycled materials comprising organic substances . The method is run in an arrangement 100 the main parts or components of which comprise plurality of furnaces . The arrangement 100 may be a part of a pyrometallurgy plant . In one embodiment the arrangement comprises two furnaces 1 , 1c as shown in Figure 1 . In another embodiment , the arrangement comprises three furnaces la- lc as shown in Figure 2 .

The method and the arrangement 100 are controlled through the control unit 12 , which may be a computer, a computation unit or a device comprising at least one processor and a memory .

In one embodiment , the furnace is a tiltable and rotatable top blown rotary converter . The top blown rotary converter is shaped like an open-ended barrel and its inside lined with refractory material . The top blown rotary converter 1 can be rotated about its longitudinal axis X and tilted about an axis Y perpendicular to said longitudinal axis X as shown in Figures 3 and 4 .

In one embodiment , such as shown in Figures 3 and 4 , the top blown rotary converter comprises not only a mouth 2 but also at least one taphole 3 separate from said mouth 2 . In one embodiment , the the top blown rotary converter has one taphole 3 . In another embodiment , there is a plurality of tapholes 3 , such as two , three , four or even more . In one embodiment , the top blown rotary converter 1 does not comprise the separate taphole ( s ) .

At the beginning of the method, it is fed or loaded a batch of recycled coarse material into a first furnace 1 of the furnaces through a mouth 2 thereof . Said recycled coarse material may comprise e . g . recycled coarse material that has been generated within the pyrometallurgy plant . Said recycled coarse material may comprise e . g . slag lumps , that contains metal oxides , blocks of material scraps comprising metal (s) , such as copper, etc. In one embodiment, particles or lumps of this material have typically size up to tens of centimetres, or even more.

During the feeding of the coarse material, the first furnace 1 may be positioned in an alternative position, for example in an upright position. In the loading it is used a coarse material charging arrangement 4, comprising, e.g., a skip hoist or a feeding boat.

As the first furnace 1 is filled with a desired amount of coarse material, it is preheated to a temperature that is sufficient for combusting organic substances (that will be fed in the following method step in the first furnace 1) , but below melting temperature metal or metals to be fed therein. In one embodiment, the first furnace 1 is positioned at an incline, such as shown in Figure 3, during the preheating. In one embodiment, the preheating is realized by a heating system comprising at least one burner, such as gas burner, or electric heaters. In one embodiment, the heating system comprises a burner lance 14 supplied with natural gas .

In one embodiment, the first furnace 1 is rotated slowly around its longitudinal axis X for minimizing dust emissions during the preheating process. In one embodiment, rotational speed during the preheating process is in range of 1 - 3 rounds per minute.

After the desired temperature has been reached in the preheating, a continuous feeding of a main recycled material 20 is started. The term "continuous feeding" does not preclude short interruptions in introducing the main recycled material in first furnace 1. The main recycled material is typically crushed in form of particles and fragments , and its s i ze is typically substantially finer than the coarse material . The main recycled material may originate from many sources . In one embodiment the main recycled material compri ses electronic scrap , cable scrap, and plastic scrap from electrical or electronic devices . In one embodiment the main recycled material comprises insulation or isolation materials that comprises organic material and metal , such as copper .

In one embodiment , the first furnace 1 is rotated around its longitudinal axis X while feeding the main recycled material with a higher rotational speed than in the preheating . This is for maintaining a sufficient and homogeneous reaction environment in the top blown rotary furnace . In one embodiment , rotational speed during the continuous feeding of the main recycled material is in the range of 3 - 10 rounds per minute .

In one embodiment , the main recycled material is continuously introduced into the first furnace through the mouth 2 by means of material gravity coupled with pneumatic transport gas , e . g . pressuri zed air . In one embodiment , said feeding is reali zed by a feeding lance 15 .

In one embodiment , the feeding arrangement 13 ( as shown in Figure 3 ) comprises an upstream feeding system 6 that is arranged for receiving recycled material from one or more material sources . The upstream feeding system 6 may comprise multiple units , for instance conveyors . Regardless of the number of units or material sources , the upstream feeding system 6 is preferably controlled so that it provides one continuous flow, where the material quantity is kept as constant as possible regardless of the material flow setpoint and transport speed . In one embodiment , the recycled material is fed from the upstream feeding system 6 into the first furnace 1 , optionally through the feeding lance 15 . In another embodiment , such as shown in the Figures , the feeding arrangement 13 is provided with a charge bin system 7 that is arranged to receive the recycled material from the upstream feeding system 6 into a charge bin, and feed said material continuous ly from the charge bin into the first furnace 1 , typically through the feeding lance 15 .

The charge bin system 7 may ensure a continuous supply of the recycled material into the first furnace , even if the upstream feeding system 6 faces malfunctions . The charge bin system 7 comprises one or more charge bins . In one embodiment , the charge bin system 7 comprises a weighing scale to monitor the feeding material ' s weight . The weighing scale may provide valuable weight data for predictive guidance and adj ustment of the upstream feeding system .

The expulsion of organic substances occurs through a combustion reaction with oxygen . This exothermic reaction generates high temperatures in the first furnace , thanks to the high heat values of organic substances , especially plastics . The method is controlled such that temperature is sufficient for maintaining the combustion of organic substances but below the melting temperature of metal ( s ) in the recycled material , and such that said combusting generates a reductive atmosphere that prevents , or at least substantially reduces , the oxidation of metal ( s ) in the first furnace .

In one embodiment , the temperature sufficient for maintaining the combustion of organic substances but below the melting temperature of metal ( s ) in the recycled material is selected such that it is 100 ° C - 400 ° C below the melting temperature of the metal ( s ) in the recycled material . The combustion reactions taking place in the first converter are typically not complete ones but result in a significant amount of reductive and combustible off-gases , such as carbon monoxide and hydrogen . The reductive atmosphere in the domain helps prevent unwanted oxidation of valuable metals .

In one embodiment , off-gas created in the combustion of organic substances is guided out from the first furnace 1 into a primary gas handling arrangement 5 through a gas hood 17 . Said off-gas comprises typically semi-combustion products , mainly CO and H2 , together with oxygen-depleted fumes , water vapor, and nitrogen .

In one embodiment , the primary gas handling arrangement 5 comprises a post-combustion unit 10 , a primary cooling unit 11 and gas cleaning system 19 . The post-combustion of the off-gas is performed in the post-combustion unit . A feeding rate and an oxygen addition ratio are carefully control led to maintain a sufficient degree of combustion and a suitable domain temperature , which is not far from the melting temperature of the batch material (AT ~ 100 ° C - 400 ° C, such as 200 -300 ° C) . Said oxygen addition may be reali zed by an air feed 18 , for instance .

Following the post-combustion unit 10 , the off-gas proceeds into the primary cooling unit 11 for cooling . Subsequently, off-gas undergoes cleaning and further cooling in a gas cleaning system 19 , from which cleaned and cooled off-gas exits the arrangement . Exiting of f-gas has typically temperature below 100 ° C and contains a relatively small amount of dust . These characteristics allow a reliable measurement of the CO ( carbon monoxide ) and CO2 ( carbon dioxide ) contents of said off-gas . According to an aspect , the des ired CO content target is zero or as close to zero as possible . The continuous feeding of the main recycled material is continued until its amount reaches the predefined batch quantity in the first furnace 1 .

After the combustion reaction in the first furnace 1 , the remaining material no longer contains organic compounds . The end of the combustion reaction can be theoretically calculated or estimated on basis of the characteristics of the recirculated material , or observed by measurements , such as decreasing temperature of the first furnace 1 or material therein . The remaining material is in a softened solid state , poss ibly with some liquid phases . Then the temperature of the first furnace 1 is raised to or over melting temperature of metal ( s ) in the first furnace 1 in order to melt said metal ( s ) . In one embodiment , said temperature is about 1300 ° C . In one embodiment the burner lance 14 is used here . In this connection, the rotational speed may be increased to ensure adequate agitation .

In one embodiment , the melting stage 21 comprises at least two semi-combustion steps each followed by the melting step . Figure 5 illustrates one embodiment comprising two semicombustion steps 22a, 22b each followed by the melting step 23a, 23b . These methods comprising multiple semi-combustion steps and melting steps , a smelting slag that is created in the melting step is discharged 28 from the furnace prior to the following semi-combustion step . Said discharging may include skimming .

The multiple semi-combustion steps and melting steps including discharging slag between the melting step and the following semi-combustion step may create more space within the furnace , and thus enhanced production capacity of the furnace may be provided . In one embodiment , the main recycled material is fed 20 continuously in at least two semi-combustion steps 22a, 22b . In one embodiment , the main recycled material is fed 20 in all the semi-combustion steps .

Using a two-feed step process as an example, illustrated in Figure 5 , the first semi-combustion step 22a involves loading all the needed recycled coarse material 29 into the furnace , followed by the continuous feeding 20 of main recycled material for the semi-combustion reaction . The amount of the main recycled material fed during the first semicombustion step 22a is half or substantially half of the total amount of material required for a batch cycle . Subsequently, the first melting step 23a, including settling, is carried out to produce melting slag and black copper . In this stage , only the melting slag 28 is discharged, e . g . , skimmed, from the first furnace through its mouth 2 , while the liquid black copper remains ins the furnace .

In one embodiment , the black copper comprises copper and ferrous and non-ferrous metals , typically including silver, gold, palladium, platina .

Following discharging the melting slag 28 , the remaining, i . e . , not yet fed, main recycled material 20 is continuously fed as a second feed step into the furnace 1 and the second semi-combustion step 22b is performed substantially similar way as the first semi-combustion step 22a .

The furnace ' s temperature is increased in order to melt the material therein . A certain amount of black copper already exists in the furnace when the second feed-step begins . Thi s may alter the relationship between the slag and the black copper . Therefore , in one embodiment , the feeding amount relationship between the slag forming fluxes that comprises various oxides , and the main recycled material is adj usted during the second feed-step to optimize the slag composition .

According to an aspect, the primary goal of the melting stage 21 is to transform the heated material, devoid of organic components, into molten slag and black copper. Additional heat may be contributed by, e.g., the burner lance 14. The rotation speed of the furnace may be increased to achieve sufficient agitation of the material inside. As melting is progressing, the added slag forming fluxes melt and form molten slag. Once the melting stage is completed, the slag composition is finalized and, if necessary, additional fluxes are added therein. Before tapping the slag, a certain waiting time may be needed to allow the metal droplets to settle from the slag phases back into the metal phase. Once the melt reaches the correct composition, the slag is tapped from the furnace mouth 2 and fed into a slag cleaning process, such as shown in Figure 6, whereas the black copper subjected to a converting stage 25.

In the converting stage 25, the material in the furnace is separated into two phases: a slag phase S and a liquid or melted metal phase M. In one embodiment, the metal phase M comprises raw copper. In one embodiment, the raw copper contains over 96 weight-% copper.

In one embodiment where the converting stage 25 is implemented in the first furnace 1, i.e., in the same furnace with the melting stage 21, such as shown in Figure 1, the arrangement 100 comprises three lances for feeding materials in the first furnace: a burner lance 14, a feeding lance 15 and a converting lance 55 for oxidation refining. The converting lance 55 is supplied with a mixture of oxygen and compressed air to create an oxygen-enriched gas. In another embodiment, such as shown in Figure 2, the converting stage 25 is implemented in a second or separate refining furnace lb separate from the first furnace la. One embodiment of the refining furnace lb is shown in Figure 7. Therefore, the black copper 64 is discharged from the first furnace la through the taphole (s) 3 (if any) or the mouth 2 into e.g. a ladle, transported to the refining furnace lb and introduced thereto, e.g., through a charging funnel 16 shown in Figure 7.

In one embodiment, copper scrap, recycled materials, and slag formers are charged into converting stage 25. The liquid metal present in the furnace acts as a "heel" to protect the refractory lining during the feeding of solid materials. After material charging, the burner lance 14 and the converting lance 55 are inserted into the furnace where the converting stage 25 is taking place. The converting lance 55 is preferably positioned close to the melt surface to ensure efficient refining.

In one embodiment, the converting stage 25 comprises multiple steps, such as in a double-step converting procedure shown in Figure 8. In the first step 25a of the converting stage, the method may comprise adding copper scrap 31, Cu- Ni alloy 32 and/or silicate dross 68 in the black copper. Oxygen-enriched gas, from the converting lance for instance, is blown onto the material surface with ultrasonic velocity. High gas velocity significantly enhances the diffusion of oxygen into the metal phase, thereby promoting the oxidation reaction thereof. This oxidation reaction generates energy, which leads to a reduced fuel consumption. Simultaneously, the furnace 1 or the refining furnace lb may be operated at a high rotation speed to facilitate the oxidation reaction and achieve composition homogenization. In the oxidation reaction most of iron (Fe) , lead (Pb) , tin (Sn) , and zinc (Zn) , along with some copper (Cu) and nickel (Ni) , are oxidi zed and subsequently they become components of the slag phase . Consequently, the slag volume continuously increases during the converting process , and it may become necessary to perform multiple slag skimming operations where slag is discharged from the furnace . The obtained refining slag is discharged 26 . In one embodiment , said discharged slag is transported to further processing, such as to a recovering process shown in Figure 10 .

Following the discharging of the refining slag and optional addition of additional slag forming fluxes , a second step 25b of the conversion is carried out using in principle the same method as in the first step . The converting stage 25 produces purified metal , referred to as raw copper, that in one embodiment contains over 95 weight-% copper, and secondary oxidation slag .

In one embodiment , said secondary oxidation slag 30 that may contain a high copper content , is allowed to solidify, crushed, and then reintroduced into the converting stage of a following batch .

In one embodiment , the raw copper is e . g . poured into a ladle and then transported to a further refining, such as to an anode furnace 42 , where it is processed 42 into a refined anode copper 44 .

In one embodiment , the anode furnace 42 is refractory-lined and has a cylindrical shape .

In one embodiment , copper scrap 31 is added in the raw copper in the anode furnace 42 . Said copper scrap 31 may comprise copper scrap recycled in the method and/or copper scrap coming from external sources . The heat required for melting the scrap is generated by a heater, such as a high- powered burner . To facilitate the process , processing gases , such as air, for oxidation, and natural gas for reduction, are inj ected into the anode furnace 42 . Nitrogen may also be inj ected into the anode furnace , for instance through porous plugs that promotes reaction kinetics by providing agitation at the bottom of the anode furnace . The nitrogen inj ection process is controlled by the porous plug unit .

At the start of an anode furnace batch, the feed material is introduced into the furnace through the furnace mouth . In one embodiment , the liquid raw copper is charged into the anode furnace 42 before the solid materials , so that said liquid raw copper protects the refractory lining of the furnace against hits and rubbing of solid materials . In one embodiment , once all the batch is loaded, the heater is adj usted to a melting mode . During the melting process , the copper undergoes oxidation to remove the maj ority of impurities , which are transferred to a slag phase . Once the process i s complete , the resulting slag, often referred to as anode s lag, i s gently discharged from the furnace into , e . g . , a ladle . I f there is a substantial volume of anode slag, it can be discharged in multiple steps . The anode slag 46 may be fed in the melting stage 21 of a following batch .

After the oxidation and removal of the anode slag, any excess oxygen in the melt may be eliminated by inj ecting natural gas in the anode furnace . In one embodiment , the refined anode copper 44 comprises at least 99 weight-% copper . The refined anode copper 44 is discharged from the anode furnace and casted into ingots once the reduction is complete and the copper quality and temperature meet the required standards .

Figure 6 illustrates a slag cleaning process 24 of a method for recovering metal from recycled materials comprising organic substances . In one embodiment , the melting slag 28 that is discharged from the melting stage 21 is arranged in a ladle or similar, and then transferred and poured into a dedicated settling unit 38 , such as a furnace or ladle with a heater . This unit 38 provides the required high temperature and sufficient residence time for separating metal droplets from the slag such that a black copper phase and a settled slag phase are separated . Following the settling stage , a settled slag phase 67 is discharged and transported to a slag granulation station 33 , while the settled black copper phase 39 is transported back to the converting stage for a refining treatment .

The granulation station 33 granulates said settled slag phase 67 . In one embodiment , the granulation station uses a method where the slag is melted and molten slag is poured from a ladle into a slag launder, with its tilting velocity controlled according to preset parameters . As it reaches the end of the launder, the slag stream descends and encounters a high-powered water j et stream delivered through a granulation noz zle . Thi s intense interaction causes the slag flow to fragment into small droplets , which rapidly cool and solidify into fine granules . The granule si ze typically ranges in the order of several millimeters and can be f ine-tuned by adj usting various process parameters such as slag temperature , pouring speed, granulation water pressure , and noz zle design . These granules are directed into the granulation pit along with the water and are subsequently collected using a suitable device , such as a bucket conveyor elevator . The gathered granules are then deposited onto a dewatering screening system and subsequently transported to a separation process 34 .

The granulated slag is separated to a metal rich phase 35 and a discarded slag 36 . In one embodiment , the separation process 34 is based on a magnetic separation method . The reductive condition in the melting stage 21 causes that a certain amount of ferrous oxides are reduced to metallic iron, which renders the black copper phase magnetic . In one embodiment , the granulated slag is conveyed into a feeder, such as a vibrating chute feeder or a screw feeder, and then fed into the separator . The fine , powdery nature of the slag resulting from the granulation treatment provides a large specific surface area, which is advantageous for the magnetic separation method . The magnetic materials adhere to the magnetic section, and upon reaching a specific boundary point , such as a baffle, they detach from the separator and fall into a collection container . These materials constitute the metal rich phase 35 that is recycled back into the melting stage 21 . The non-magnetic materials , on the other hand, do not adhere to the separator . They fall into a separate container or onto a transport unit and discharged as the discarded slag 36 .

The separation process 34 may be repeated if needed to increase the separation yield . The final non-magnetic material or discarded s lag 36 may then be transported to and stored in, e . g . , a granule bunker . In one embodiment, after magnetic separation the total copper in the non-magnetic material is about 0 . 7 weight-% or less .

The metal rich phase 35 separated from the discarded slag 36 , i . e . material having less metal , by magnetic force contains metal grains as well as a certain amount of slag phase . In contrast , the discarded slag 36 primarily consists of powdery slag .

While it ' s desirable to achieve a high copper separation rate in the magnetic separation process , it ' s crucial to consider the presence of copper-containing non-magnetic materials . The magnetic flux dens ity also significantly influences to the separation efficiency . Too low magnetic force does not effectively separate the metal-rich magnetic materials , while excessively high magnetic force increases the slag phase in the metal rich phase . The optimal magnetic flux density varies depending on factors like the slag supply rate to the separating proces s 34 . Thus , the magnetic flux is adj usted based on the speci fic operating conditions and the required copper separation rate .

Figure 9 is a schematic view of a still further step of a method for recovering metal from recycled materials comprising organic substances in partial cross-section, and Figure 10 illustrates a fourth stage of a method for recovering metal from recycled materials comprising organic substances .

The refining s lag 26 originating from the converting stage 25 may contain signif icant quantities of lead ( Pb) and tin ( Sn) oxides , in addition to iron ( Fe ) , copper (Cu) , nickel (Ni ) and their respective oxide phases . There may also be a certain amount of silica and alumina present in the slag . In one embodiment , the valuable refining slag is subj ected to a reduction or recovering process 47 that may take place in a separate slag recovery furnace 1c, such as shown in Figure 9 .

In one embodiment , the refining slag 26 from the furnace 1 , or in embodiments where the converting stage 25 is carried out in a separate furnace from the refining furnace lb, is recovered 47 in the separate slag recovery furnace 1c . In one embodiment , a lead-tin ( Pb-Sn) alloy is produced in said recovering . The Pb-Sn alloy may then be purified in a drossing unit 58 for producing refined Pb-Sn alloy 60 . According to an aspect , said refined Pb-Sn alloy is another main product of the method together with anode copper . Byproducts obtained from the slag recovery furnace 1c and the drossing unit 58 may be reintroduced into the furnace 1 or the refining furnace lb .

In one embodiment , the first step 47a of the recovering of the refining slag 26 comprises adding to the refining slag at least one reduction agent 48 , such as burning metallurgical coke . This introduces heat and carbon monoxide in the slag recovery furnace 1c .

In one embodiment , the reduction agent 48 , such as said coke , initially reacts with oxygen to produce carbon monoxide . The carbon monoxide then acts to reduce the oxides in the refining slag to produce metal or lower oxides . The order of reduction follows the decreasing oxygen affinity of different metallic elements , with the intention of reducing the element with the weakest oxygen affinity first .

During the first step 47a where the reduction agent is added, the maj ority of the copper (Cu) and nickel (Ni ) are reduced from the slag, forming a distinct metallic phase known as a Cu-Ni liquid alloy . Simultaneously, small quantities of lead ( Pb ) and tin ( Sn) may also be generated as byproducts in the metal phase through undesired side reductions .

As a result , the slag undergoes a transformation or refining 49 into two immiscible phases : the Cu-Ni alloy in liquid form and a slag known as Pb-Sn slag . Said Pb-Sn contains high concentrations of Pb- and Sn-oxides . The Cu-Ni alloy is s ituated beneath the Pb-Sn slag inside the TBRC furnace due to its greater density .

In one embodiment , the Pb-Sn slag is skimmed into a ladle etc . equipped with a heater to maintain the slag in a liquid phase . Following the removal of the Pb-Sn-slag, the Cu-Ni alloy is poured into another ladle and cast into ingots . These Cu-Ni ingots may then be reintroduced into the process by feeding them into the converting stage 25 .

As the Cu-Ni alloy has been discharged 50 from the slag recovery furnace , recovering of said Pb-Sn slag is continued in a second step 47b of the recovering of the refining slag by recharging said Pb-Sn slag back into the slag recovery furnace 1c by using, e . g . , a boat 37 .

During the second step 47b, additional reduction agent 48 may be added to the slag recovery furnace 1c for converting the Pb- and Sn-oxides within the Pb-Sn-slag phase into a metallic form, resulting formation 51 of a crude Pb-Sn alloy . A discarded slag 36 is also formed . The discarded slag 36 is often devoid of valuable metals and is removed from the method and the arrangement . In one embodiment , the discarded slag 36 is reintroduced in the first furnace 1 .

The crude Pb-Sn alloy typically contains certain amounts of impurity elements like copper (Cu) , nickel (Ni ) , and iron ( Fe ) . The impurities may constitute up to about 10 weigh-% of the crude Pb-Sn alloy . In one embodiment , the share of the impurities is minimi zed or at least reduced by melting and mixing crude Pb-Sn alloy with s ilicon containing material 52 .

Due to the significantly lower density of the silicon containing material compared to the melted crude Pb-Sn alloy, a strong mixing force may be necessary to facilitate integration of said materials . In one embodiment , a defined amount of a reagent is initially placed at the bottom of a ladle 57 . Said reagent may comprise silicon containing material , for instance . When the Pb-Sn alloy is discharged from slag recovery furnace 1c into this ladle , a vigorous fluid turbulence is provided by a suitable mixer ( s ) for ensuring efficient melting 53 and mixing 54 of the reagent into the melt.

In one embodiment, the composition of the crude Pb-Sn and the silicon containing material 62 is transferred in a drossing unit 58. In one embodiment, the drossing unit 58 is a melting furnace , such as an induction furnace, equipped with a stirring function. A protective atmosphere created by, e.g., a vacuum or inert gas, is maintained in the drossing unit.

The temperature within the drossing unit 58 is gradually lowered at a controlled rate. Throughout the cooling process, various types of silicate inclusions, such as FeSi, NiSi2, CusSi, and Cu_xNi_yFe_zSi, precipitate from the molten composition. These inclusions have a significantly lower density than the melt, which enables them to float to the surface of the melt, aided by a stirrer or a mixer, such as an electric magnetic stirrer. At the surface of the melt, the inclusions coagulate with each other and form clusters of dross. The silicate dross 68 is discharged 61 from the drossing unit 58 by, e.g., tilting and skimming 59.

As the precipitation and coagulation continue in the drossing unit 58, the amount of silicate dross increases over time. Consequently, multiple discharging operations may be necessary in order to guarantee an effective separation. However, as the silicon content in the melt is gradually depleted, the rate of dross formation decreases. Therefore, the rate of dross formation may become negligible or even cease entirely after reaching a certain temperature. Once the dross formation and discharged processes are finished, the melt, containing only trace amounts of undesired elements, e.g., less than 1 mass% copper, may further be cooled and cast into ingots. These ingots can be further refined or processed as a marketable alloy. The silicate dross 68 discharged from the dross ing unit 58 may contain valuable metals like Cu and Fe . Thus , in one embodiment , it is recycled into the converting stage 25 .

The invention is not limited solely to the embodiments described 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 conj unction with or replace the attributes of another embodiment or application .

The drawings and the related description are only intended to i llustrate the idea of the invention . The invention may vary in detail within the scope of the inventive idea defined in the following claims .

REFERENCE SYMBOLS

1 furnace

2 mouth

3 taphole

4 coarse material charging arrangement

5 primary gas handling arrangement

6 upstream feeding system

7 charge bin system

8 off-gas

9 cleaned off-gas

10 post-combustion unit

11 primary cooling

12 control unit

13 feeding arrangement

14 burner lance

15 feeding lance

16 charging funnel

17 gas hood

18 air feed

19 gas cleaning system

20 feeding main recycled material

21 melting stage

22 semi-combustion step

23 melting step

24 slag cleaning process

25 converting stage

26 refining slag

27 discharging the raw copper

28 melting slag

29 feeding coarse material

30 secondary oxidation slag

31 adding Cu scrap

32 adding Cu-Ni alloy

33 granulating

34 separating 35 metal rich phase

36 discarded slag

37 boat

38 settling

39 settled black copper phase

42 anode furnace

43 processing raw copper

44 refined anode copper

45 adding slag forming fluxes

46 anode slag

47 recovering the refining slag

48 adding a reduction agent

49 converting the refining slag

50 discharging Cu-Ni alloy

51 formation of crude Pb-Sn alloy

52 silicon containing material

53 melting

54 mixing

55 converting lance

56 feeding the silicate dross

57 ladle

58 drossing unit

59 skimming

60 refined Pb-Sn alloy

61 discharging silicate dross

62 crude Pb-Sn and silicon containing material

63 inorganic agglomerates

64 black copper

65 black copper and inorganic agglomerates

66 refined black copper

67 settled slag phase

68 silicate dross

100 arrangement

Cu-Ni copper-nickel alloy M melted metal

Pb-Sn lead-tin slag

R rotation

S slag T tilting

X longitudinal axis

Y perpendicular axis

Claims

1. A method for recovering metal from recycled materials comprising organic substances, the method comprising:

- feeding continuously a main recycled material (20) , comprising said organic substances, into a furnace (1) until a predetermined batch quantity is reached,

- implementing a melting stage (21) comprising a semi-com- bustion step (22) followed by a melting step (23) , wherein

- in said semi-combustion step a sufficient temperature for combusting organic substances but below the melting temperature of said metal is maintained, combusting said organic substances and generating a reducing atmosphere, preventing the undesired oxidation of the metal in the furnace (1) , and

- in said melting step following combustion of said organic substances, raising the temperature to or over melting temperature of said metal, and

- discharging melted slag and feeding it to a slag cleaning process (24) , wherein

- following the melting stage, implementing a converting stage (25) for converting remaining material into a refining slag and a raw copper,

- discharging the refining slag (26) from the furnace (1) , and

- discharging the raw copper (27) from the furnace (1) into a further Cu processing stage.

2. The method as claimed in claim 1, wherein the melting stage comprises at least two semi-combustion steps (22a, 22b) , each followed by the melting step (23a, 23b) , and

- discharging a smelting slag (28) created in the melting step prior to the following semi-combustion step.

3. The method as claimed in claim 2, wherein the melting stage comprises

- a first semi-combustion step (22a) ,

- a first melting step (23a) ,

- a second semi-combustion step (22b) as the last of the semi-combustion steps, and

- a second melting step (23b) as the last of the melting steps .

4. The method as claimed in claims 2 or 3, comprising

- feeding continuously the main recycled material (20) in at least two semi-combustion steps.

5. The method as claimed in claim 4, comprising

- feeding the main recycled material (20) in all the semicombustion steps.

6. The method as claimed in any of the preceding claims, comprising

- feeding a batch of coarse material (29) in at least one semi-combustion step.

7. The method as claimed in any of the preceding claims, wherein

- the main recycled material comprises electronic scrap, cable scrap, plastic scrap from electrical or electronic devices, insulation or isolation materials, or any combinations thereof.

8. The method as claimed in any of the preceding claims, wherein

- said converting stage comprises at least two converting steps, wherein

- following the first of said converting steps (25a) , discharging refining slag (26) and continuing converting remaining refined black copper in a next converting step (25b) ,

- discharging secondary oxidation slag (30) from said next converting step back to the first of said converting steps and

- discharging the raw copper (27) from the last of said at least two converting steps into the further Cu processing stage .

9. The method as claimed in any of the preceding claims, comprising

- adding copper scrap (31) and/or slag forming fluxes (45) in the converting stage (25) .

10. The method as claimed in any of the preceding claims, comprising

- converting the black copper into a refined black copper by adding therein Cu-Ni alloy (32) .

11. The method as claimed in any of the preceding claims, comprising

- granulating (33) the slag received from the melting stage (21) into a granulated slag, and

- separating (34) the granulated slag to a metal rich phase (35) and a discarded slag (36) .

12. The method as claimed in claim 11, comprising

- separating (34) the granulated slag by using a magnetic separation method.

13. The method as claimed in claim 11 or 12, comprising

- feeding the metal rich phase (35) in the melting step of a following batch.

14. The method as claimed in any of claims 11-13, comprising - allowing the slag to settle (38) prior to its granulation, such that a black copper phase and a settled slag phase are separated, and

- granulating (33) said settled slag phase.

15. The method as claimed in claim 14, comprising

- feeding the black copper phase (39) back in the converting stage for converting into a refined black copper.

16. The method as claimed in any of the preceding claims, comprising

- running the melting stage and the converting stage in a same furnace (1) .

17. The method as claimed in any of claims 1-15, comprising

- running the melting stage (21) and the converting stage in separate furnaces by

- running the melting stage in a melting furnace (la) ,

- feeding the black copper (64) from the melting furnace in a separate refining furnace (lb) , and

- running the converting stage (25) in said refining furnace .

18. The method as claimed in any of the preceding claims, comprising

- discharging raw copper (27) from the converting stage (25) into an anode furnace (42) , and

- processing (42) said raw copper into a refined anode copper (44) .

19. The method as claimed in claim 18, comprising

- adding copper scrap (31) in said raw copper in the anode furnace ( 42 ) .

20. The method as claimed in claim 18 or 19, comprising - discharging anode slag (46) from the anode furnace (42) , and

- feeding said anode slag in the melting stage (21) of a following batch.

21. The method as claimed in any of the preceding claims, comprising

- recovering the refining slag (47) originating from the converting stage (25) in a separate slag recovery furnace (1c) , wherein said recovering comprises

- adding to the refining slag a reduction agent (48) and

- converting the refining slag (49) into Pb-Sn slag and Cu- Ni alloy,

- discharging said Cu-Ni alloy (50) from the slag recovery furnace,

- continuing recovering said Pb-Sn slag in a further reduction step (47b) by adding a reduction agent (48) therein for producing a crude Pb-Sn alloy,

- mixing the crude Pb-Sn with silicon containing material (52) and

- melting (53) composition thus created, and

- mixing (54) said composition for producing a refined Pb- Sn alloy and silicate dross.

22. The method as claimed in claim 21, comprising

- feeding said Cu-Ni alloy (55) into the converting stage of a following batch.

23. The method as claimed in claim 21 or 22, comprising

- feeding the silicate dross (56) in the converting stage of a following batch.

24. The method as claimed in any of claims 21-23, wherein

- mixing the crude Pb-Sn with silicon containing material (52) and melting (53) composition thus created in a ladle

25. The method as claimed in any of claims 21-24, comprising

- processing the composition of the crude Pb-Sn and the silicon containing material in molten state in a drossing unit (58) ,

- maintaining a protective atmosphere in the drossing unit,

- cooling the composition in the drossing unit gradually,

- precipitating silicate inclusions from the composition during said cooling, and

- allowing said silicate inclusions to coagulate and form silicate dross on the surface of the melt.

26. The method as claimed in claim 25, comprising

- skimming (59) said silicate dross from the drossing unit (58) .

27. The method as claimed in claim 25 or 26, comprising

- discharging a refined Pb-Sn alloy (60) from the drossing unit (58) .

28. The method as claimed in any of claims 25-27, comprising

- discharging a silicate dross (61) from the drossing unit (58) , and

- feeding said silicate dross (56) in the converting stage of a following batch.

29. The method as claimed in any of the preceding claims, wherein

- the furnace (1, la, lb, 1c) is a tiltable and rotatable top blown rotary converter.

30. An arrangement (100) for carrying out the method for recovering metal from recycled materials comprising organic substances as claimed in any of the preceding claims.