A process for converting copper matte

Abstract

The present application relates to a converter rich in copper matte method, belong to copper dross processing technical field. The present application includes dosing, feeding, reduction smelting, heat preservation precipitation, slagging, cooling the remaining slag crust, mixed melt and mixed melt separation and other implementation steps. The present application shortens the feeding time, the slag, copper matte and crude lead three separation thoroughly, the slag contains Cu, Pb low, copper matte grade high, crude lead contains low copper; without using holding furnace or settling furnace, saves the plant and equipment investment; in the furnace and ingot mold through natural cooling separation slag, copper matte and crude lead, saves the energy, reduces the carbon emission.

Description

Technical Field

[0001] This invention belongs to the field of copper slag treatment technology, specifically, it relates to a method for enriching matte in a converter. Background Technology

[0002] A small amount of copper is associated with lead concentrate. Copper enters the crude lead during the lead smelting process. When copper is removed from the crude lead during melting, it enters the copper slag. The copper slag generally contains 10-30%wt Cu and 50-70%wt Pb. In addition, the copper slag is also rich in precious metals such as silver and gold. It must be recycled to separate copper from lead, thereby improving the lead recovery rate. The recovery of copper can also improve the economic benefits of enterprises.

[0003] Previously, reverberatory furnaces were commonly used for processing copper slag. The advantage of reverberatory furnaces was the thorough separation of slag, matte, and crude lead. However, their disadvantages included low heat utilization and low hearth capacity. Therefore, reverberatory furnaces have been listed as obsolete equipment, and manufacturers are gradually using converters to smelt copper slag. However, the biggest drawback of converter smelting of copper slag is the incomplete separation of slag, matte, and crude lead. Slag and matte are often mixed together, as are matte and crude lead, and sometimes slag and matte are even mixed together, severely degrading the quality of the matte.

[0004] For example, patent CN101358286A discloses a method for treating copper slag using a converter. This method involves feeding the slag in two stages, which takes 2 to 3 hours. The long feeding time, the subsequent cooling of the furnace after the slag and matte are discharged, and the subsequent discharge of coarse lead, all contribute to the long process and reduce the converter's processing capacity. Furthermore, the slag and matte are not separated, and the mixing of the slag and matte reduces the copper content of the matte. Patent CN104263951A discloses a method for treating copper slag in a rotary furnace using a pure oxygen side-blown molten pool. This method has several drawbacks: First, the crude lead is siphoned out of the furnace from the siphon channel at the furnace end, resulting in a complex converter structure. Furthermore, a certain amount of crude lead remains at the bottom of the converter during siphoning, occupying converter volume and reducing the amount of material fed per furnace. Second, the 1-2 hour settling period after smelting is too long and requires heat preservation, leading to high fuel consumption. Third, the small difference in melting points between matte and slag makes it difficult to implement a method where matte and slag are released together for settling and separation outside the furnace. In effect, sending matte and slag together to copper smelting (as shown in the process flow diagram in the attached drawings) reduces the copper content of the matte. Patent CN105838894A discloses a process for treating copper dross using oxygen-enriched top-blown smelting and settling separation. The process involves adding copper dross and other materials to an oxygen-enriched top-blown converter for smelting, then transferring the melt from the converter to a holding furnace where oxygen is blown in for settling separation. From the holding furnace, slag, matte, and crude lead are separated sequentially. The drawbacks are that it requires oxygen enrichment and two furnaces—an oxygen-enriched top-blown converter and a holding furnace—to complete the smelting of the copper dross and the separation of slag, matte, and crude lead. This results in a large initial investment, high energy consumption, and high carbon emissions per unit volume of copper dross processed.

[0005] Currently, there is no existing technology that can completely separate slag, matte, and crude lead during copper slag converter smelting with low energy consumption and low carbon emissions. Summary of the Invention

[0006] In order to overcome the problems existing in the prior art, the present invention provides a method for enriching copper matte in a converter, which can completely separate copper matte, crude lead and slag.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: The method for enriching copper matte in a converter involves first adding copper slag to a mixture of soda ash, iron filings, and raw coal, then adding it to the converter for smelting. After smelting, the mixture is kept at a constant temperature and allowed to settle. Following this settling process, the method also includes the following steps: S1: Discharge molten slag; S2: Cooling causes the remaining slag to solidify into a shell; S3: Discharge the mixed melt into the ingot mold, and insert a hook into the upper part of the ingot mold; S4: The solidified copper matte at the top of the ingot mold is lifted out using a hook, and then a hook is placed in the molten lead at the bottom. After the molten lead solidifies, the lead ingot is lifted out.

[0008] Further, maintain the temperature for 10-20 minutes to allow the slag to settle before discharging it.

[0009] Furthermore, through steps S1 and S2, the slag is separated from the mixed melt.

[0010] Furthermore, the cooling time in step S2 is 15-30 minutes.

[0011] Furthermore, in step S3, the mixed melt is a mixture of copper matte and crude lead.

[0012] Furthermore, the weight ratio of copper slag in the batch is copper slag: soda ash: iron filings: raw coal = 100: 4~8: 0.5~1.0: 1~3.

[0013] Furthermore, copper slag, soda ash, iron filings, and raw coal are added to the converter in one batch.

[0014] Furthermore, during smelting, the furnace temperature is controlled at 1150–1200℃, and the smelting time per furnace is 6–8 hours.

[0015] Furthermore, during the smelting process, the furnace body is rotated 2-4 times per hour, and air ducts are inserted into the melt.

[0016] Furthermore, steps S2 and S4 involve natural cooling and condensation.

[0017] Furthermore, in step S4, the time for the copper matte to naturally cool and condense is 0.5-1.0 h.

[0018] Furthermore, in step S4, the time for the crude lead to naturally cool down and condense is 1.0-1.5 hours.

[0019] Furthermore, natural gas is used as fuel for the smelting and heat preservation settling steps.

[0020] The beneficial effects of this invention are: One-time feeding shortens the feeding time, completes settling and thorough separation of slag and mixed melt within the converter, and thoroughly separates matte and crude lead within the ingot mold. The separation of slag, matte, and crude lead is thorough, resulting in low Cu and Pb content in the slag, high grade matte, and low copper content in the crude lead. There is no need to use a holding furnace or settling furnace, saving on plant and equipment investment. The separation of slag, matte, and crude lead through natural cooling within the furnace and ingot mold saves energy and reduces carbon emissions. Detailed Implementation

[0021] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are all within the scope of protection of this invention.

[0022] The method for enriching copper matte in a converter includes the following steps: Ingredients and Feeding Copper slag, soda ash, and raw coal are mixed in a weight ratio of 100:4-8:0.5-1.0:1-3. The furnace opening is then rotated to the feeding port position, and the mixed materials are added to the converter all at once to shorten the feeding time and improve the converter's processing capacity. After feeding is complete, the furnace opening is rotated to a position 30-40° above the horizontal line to prevent flue gas from overflowing.

[0023] (2) Reduction smelting Natural gas is used as fuel, compressed air is used as combustion aid, the furnace temperature is controlled at 1150-1200℃, and the smelting time of a single furnace is 6-8 hours. After the converter outlet flue gas is cooled by surface cooling and bag dust collection, sulfur dioxide is absorbed by hydrogen peroxide and then discharged into the air, and the flue gas is returned to the batching.

[0024] During the melting process, the furnace body is rotated 2-4 times per hour, and air ducts are inserted into the molten material to increase agitation and accelerate the melting and reaction speed. Failure to rotate the furnace body and insert air ducts will prolong the melting and reaction time, increasing natural gas consumption and reducing operational efficiency. Furthermore, rotating the furnace body and inserting air ducts at regular intervals is also essential for achieving one-time feeding.

[0025] (3) Heat preservation and sedimentation The furnace temperature was controlled at 1150–1200℃, and the slag was kept at this temperature for settling. The purpose of this settling process was to reduce and stabilize the Pb and Cu content in the slag. Calculations and multiple measurements showed that when the settling time was less than 10 minutes, the Pb and Cu content in the slag was high; when the settling time was greater than 20 minutes, the decrease in Pb and Cu content was not significant. To save energy, the settling time was controlled to be 10–20 minutes.

[0026] (4) Add molten slag Turn off the natural gas and compressed air supply for combustion, rotate the furnace opening to release the molten slag, and use a slag probe to check the slag layer thickness. When the molten slag thickness in the converter reaches 20-30mm, stop releasing slag. This is to prevent matte from mixing into the molten slag, which would increase the Cu and Pb content in the slag and reduce the matte yield. The condensed reduction slag is then sent to the lead smelting furnace.

[0027] When the residual slag thickness inside the converter is less than 20 mm, matte is easily mixed in during slag discharge; when the residual slag thickness is greater than 30 mm, the feed amount for the next heat will be reduced. Therefore, controlling the thickness of the residual slag layer inside the converter is crucial.

[0028] (5) Cooling causes the remaining slag to form a crust. Cooling causes the residual slag in the converter to form a crust, which prevents slag from mixing into the matte and thus reducing its quality. Measurements have shown that a cooling time of 15-30 minutes is suitable.

[0029] (6) Add the mixed melt Break up the slag crust near the converter discharge port, pour the molten mixture of matte and crude lead into the ingot mold, insert a hook into the top of the ingot mold, and then replace it with another empty mold. Repeat this process until all the molten material in the furnace has been poured out. The hook material is Q235A.

[0030] (7) After the natural cooling and condensation time is 0.5-1.0h, the condensed copper matte on the top of the ingot mold is lifted out, and then a hook is placed in the bottom lead liquid. After the natural cooling and condensation time is 1.0-1.5h, the crude lead ingot is lifted out.

[0031] Copper matte has a lower density than molten lead, and the two are immiscible. When the mixed molten material is poured in, the copper matte floats on top of the mold, while the molten lead sinks to the bottom. Furthermore, taking advantage of the significant difference in melting points between copper matte and molten lead (copper matte has a much higher melting point than molten lead), the copper matte solidifies first, followed by the molten lead. Therefore, after the mixed molten material in the mold has cooled for a certain period, a crane is used to hook and lift out the solidified copper matte from the top of the mold. Then, a hook is placed in the molten lead at the bottom, and after the lead has completely solidified, the lead ingot is lifted out, thus completing the separation of the copper matte and crude lead.

[0032] The cooling time of the matte placed in the mold needs to be controlled. If the cooling time is too short, the matte will not solidify completely, resulting in incomplete separation between the matte and the crude lead. If the cooling time is too long, the crude lead at the bottom will solidify, also resulting in incomplete separation. Through extensive testing and demonstration, it has been found that a cooling time of 0.5 to 1.0 hours for the lead-copper matte in the mold is appropriate.

[0033] After step (7) is completed, the slag crust in step (5) is broken up. The slag crust participates in the next furnace smelting. The amount of slag crust is small and does not affect the amount of material fed in the next furnace.

[0034] To illustrate the present invention more clearly, the following embodiments will be described in detail. Example 1

[0035] Copper slag, soda ash, and raw coal are mixed in a weight ratio of copper slag: soda ash: iron filings: raw coal = 100:4:1.0:1; the furnace opening is rotated to the feeding port position, and the mixed materials are added to the converter all at once; after feeding is completed, the furnace opening is rotated to a position 30° upward from the horizontal line.

[0036] Compressed air and natural gas are supplied to the furnace for ignition and heating, and the furnace temperature is controlled at 1150℃. The smelting time is 8 hours. During the smelting process, the furnace body is rotated twice per hour, and air ducts are inserted into the melt. After the flue gas from the converter outlet is cooled by surface cooling and collected by bag filter, sulfur dioxide is absorbed by hydrogen peroxide and then discharged into the air. The flue gas is returned to the batching process.

[0037] After smelting is completed, remove the air duct, keep it warm and settle for 10 minutes, then shut off the natural gas and compressed air, rotate the furnace opening to release the slag, and stop releasing the slag when the slag layer thickness is detected to be 30 mm. The condensed slag is sent to the lead smelting furnace and allowed to cool naturally for 15 minutes to allow the remaining slag to form a crust.

[0038] Break up the slag crust near the converter discharge port, pour the molten mixture of matte and crude lead into the ingot mold, insert a hook into the top of the ingot mold, and then replace it with another empty mold. Repeat this process until all the molten mixture in the furnace has been poured out. The hook material is Q235A.

[0039] After a natural cooling and condensation period of 0.5 hours, the solidified copper matte on the top of the ingot mold is lifted out. Then, a hook is placed in the bottom lead liquid, and the natural cooling and condensation period continues for another 1.0 hour before the crude lead ingot is lifted out.

[0040] The slag contains 1.48%wt of Pb and 1.01%wt of Cu; the matte contains 58.98%wt of Cu; and the crude lead contains 95.38%wt of Pb and 1.52%wt of Cu. The three components are completely separated. Example 2

[0041] Copper slag, soda ash, and raw coal are mixed in a weight ratio of copper slag: soda ash: iron filings: raw coal = 100:8:0.5:3. The furnace opening is rotated to the feeding port position, and the mixed materials are added to the converter all at once. After feeding is completed, the furnace opening is rotated to a position 30° above the horizontal line.

[0042] Compressed air and natural gas are supplied to the furnace for ignition and heating, and the furnace temperature is controlled at 1200℃. The smelting time is 6 hours. During the smelting process, the furnace body is rotated 4 times / hour, and air ducts are inserted into the melt. After the flue gas from the converter outlet is cooled by surface cooling and bag dust collection, sulfur dioxide is absorbed by hydrogen peroxide and then discharged into the air. The flue gas is returned to the batching process.

[0043] After smelting is completed, remove the air duct, keep it warm and settle for 20 minutes, then turn off the natural gas and compressed air, rotate the furnace opening to release the slag, and stop releasing the slag when the slag layer thickness is detected to be 20 mm. The condensed slag is sent to the lead smelting furnace and allowed to cool naturally for 30 minutes to allow the remaining slag to form a crust.

[0044] Break up the slag crust near the converter discharge port, pour the molten mixture of matte and crude lead into the ingot mold, insert a hook into the top of the ingot mold, and then replace it with another empty mold. Repeat this process until all the molten mixture in the furnace has been poured out. The hook material is Q235A.

[0045] After natural cooling and solidification for 1.0 hour, the solidified matte on the top of the ingot mold is lifted out, and then a hook is placed in the bottom lead molten metal. Natural cooling and solidification continues for another 1.5 hours before the crude lead ingot is lifted out. The slag contains 1.35%wt Pb and 0.79%wt Cu; the matte contains 60.87%wt Cu; and the crude lead contains 95.26%wt Pb and 1.47%wt Cu. All three components are completely separated.

[0046] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for enriching copper matte in a converter, comprising first adding copper slag to soda ash, iron filings, and raw coal as feedstock, then adding the feedstock to a converter for smelting, followed by heat preservation and settling after smelting, characterized in that... After the insulation and settling process, the following steps should be performed: S1: Discharge molten slag. Stop discharging slag when the slag thickness reaches 20-30mm. S2: Cooling causes the remaining slag to form a crust; the crust participates in the next smelting process. S3: Discharge the mixed melt into the ingot mold, and insert a hook into the upper part of the ingot mold; S4: The solidified copper matte at the top of the ingot mold is lifted out through a hook, and then a hook is placed in the molten lead at the bottom. After the molten lead solidifies, the lead ingot is lifted out. The copper slag, soda ash, iron filings and raw coal are added to the converter in one batch; During the smelting process, the furnace body is rotated 2-4 times per hour, and air ducts are inserted into the melt. After the smelting is completed, the air ducts are removed, and the process proceeds to the heat preservation and settling step.

2. The method as described in claim 1, characterized in that, Insulate and allow the material to settle for 10-20 minutes before discharging the molten slag.

3. The method as described in claim 1, characterized in that, Steps S1 and S2 separate the slag from the mixed melt.

4. The method as described in claim 1, characterized in that, The cooling time in step S2 is 15-30 minutes.

5. The method as described in claim 1 or 3, characterized in that, In step S3, the mixed melt is a mixture of copper matte and crude lead.

6. The method as described in claim 1, characterized in that, In the copper slag batching process, the weight ratio of the batching materials is copper slag: soda ash: iron filings: raw coal = 100: 4~8: 0.5~1.0: 1~3.

7. The method as described in claim 1, characterized in that, During smelting, the furnace temperature is controlled at 1150-1200℃, and the smelting time for a single furnace is 6-8 hours.

8. The method as described in claim 1 or 4, characterized in that, Steps S2 and S4 involve natural cooling and condensation.

9. The method as described in claim 8, characterized in that, The natural cooling and condensation time for copper matte is 0.5-1.0 hours.

10. The method of claim 8, characterized in that, The natural cooling and condensation time for crude lead is 1.0-1.5 hours.

11. The method as described in claim 1, characterized in that, Natural gas is used as fuel for the smelting and heat preservation settling steps.