A method for smelting tin dross in a short furnace

Abstract

The application provides a method for smelting tin ash in a short kiln, and one smelting cycle comprises more than twice of primary smelting and once of secondary smelting; the primary smelting and the secondary smelting are respectively performed on tin ash and tail slag after smelting of the tin ash; the primary smelting uses tin ash as main material and uses anthracite and scrap pig iron as auxiliary material; the secondary smelting uses the tin ash tail slag discharged from the primary smelting as main material and uses anthracite, limestone and lead scrap as auxiliary material; the primary smelting and the secondary smelting are both divided into two stages: lead smelting stage and slag smelting stage; the main material and the auxiliary material are put in during the lead smelting, and lead is discharged after the lead smelting; slag smelting is performed after the lead is discharged, and a small amount of residual lead and tail slag are discharged after the slag smelting is completed. The tin ash is smelted through two different extraction processes of the primary smelting and the secondary smelting, the residual tin element in the tail slag is extracted to the maximum extent, the tin content of the final slag can be reduced to below 1%, and the average level of tin smelting without fuming treatment is basically reached.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal smelting, specifically relating to a method for smelting tin ash in a short kiln. Background Technology

[0002] A short kiln, also known as a rotary kiln, primarily uses radiant heat from a spray gun to the furnace wall, which is then transferred to the material through rotation. Because there is no high-speed gas directly acting on the material within a short kiln, it is more adaptable to various materials and can be used for smelting materials of various properties. In the recycling of waste lead-acid batteries, short kilns are more commonly used for smelting various alloy slags, ash, and lead-containing waste.

[0003] Tin ash is a granular or powdery alloy slag produced during the tin-enriching process in alloy lead production. It has a high tin content, reaching over 20%, while the lead and antimony content is relatively low. Tin ash is a common high-value product for lead recycling companies. However, the smelting furnaces used in lead recycling companies are generally not suitable for tin smelting. Therefore, the common practice is to sell it directly to tin smelting companies, resulting in a significant discount in value. If tin ash is smelted directly using lead smelting methods, the slag will have a very high tin content, leading to considerable waste. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a method for smelting tin ash in a short kiln, which effectively reduces the tin content in the tin ash tailings and improves the tin recovery rate in the tin ash smelting process.

[0005] To achieve the above objectives, the technical solution of the present invention is: a method for smelting tin ash in a short kiln, wherein one smelting cycle includes two or more primary smelting processes and one secondary smelting process.

[0006] The primary smelting process consists of lead smelting stage A and slag smelting stage A.

[0007] Lead smelting stage A: After adding the primary smelting raw materials to the short kiln in proportion, ignite it; adjust the natural gas power to P1kW according to the amount of main material added, and after smelting for a period of time T1h, carry out the lead discharge operation. At this time, there are still some tailings in the furnace with low temperature and high lead and tin content.

[0008] Slag Refining Stage A: After lead is discharged in lead smelting stage A, the natural gas combustion power is adjusted to P2kW according to the amount of main material added. After smelting for a period of time T2h, the remaining small amount of crude lead and tin ash tailings are discharged, and the smelting is completed in one go.

[0009] The raw materials for the primary smelting process include main material one and auxiliary material one.

[0010] The main material is tin ash; the tin ash contains tin (Sn1%>20%), lead (Pb1%<60%), sulfur (S1%<1%), and the sum of antimony (Sb%) and arsenic (As%) is <5%.

[0011] The auxiliary material is anthracite and pig iron filings.

[0012] The raw materials for primary smelting are as follows, by mass: Tin gray 100; Cast iron filings C; C = 300 × S% + 50%; Anthracite A min ~A max ; A min =13×(Sn1%+As%)+3×Pb1%+7×Sb%-40×S1%; A max =16×(Sn1%+As%)+4×Pb1%+10×Sb%-35×S1%.

[0013] The secondary smelting process consists of lead smelting stage B and slag smelting stage B.

[0014] Lead smelting stage B: After collecting 12-16t of tin ash tailings from the first smelting at least twice, use a crusher to crush the main material II into blocks that can be fed into the short kiln, and then mix it with auxiliary material II into the short kiln and ignite it; adjust the natural gas power to BP1kW according to the amount of main material II added, and after smelting for a period of time BT1h, carry out the lead discharge operation.

[0015] Slag Refining Stage B: After lead is discharged in Lead Refining Stage B, the natural gas power is adjusted to BP2kW according to the amount of main material II added. After smelting for a period of time (BT2h), the remaining small amount of crude lead and tailings are discharged, and the secondary smelting is completed.

[0016] The raw materials for secondary smelting include main material 2 and auxiliary material 2.

[0017] The second main material is tin ash tailings released from smelting at least twice; the tin ash tailings contain 3% to 8% tin (Sn2%), 2% to 5% lead (Pb2%), and less than 3% sulfur (S2%).

[0018] The auxiliary material 2 is limestone, anthracite, and lead shavings.

[0019] The raw materials for secondary smelting are as follows, by weight: 100 tons of tin ash tailings; 30-50 lead scraps; Limestone 3.5~5.5; Anthracite B min ~B max ; B min =17×Sn2%+4×Pb2%+0.5×T; B max=21×Sn2%+6×Pb2%+0.7×T; T = BT1 + BT2.

[0020] The amount of main ingredient added is M tons; 75M≤P1≤90M; 0.10M≤T1≤0.15M. 70M≤P2≤75M; 0.07M≤T2≤0.08M.

[0021] The addition amount of main ingredient 2 is m tons; 0.13m≤BT1≤0.16m; 120bm≤BP1≤140m. 0.2m≤BT2≤0.25bm; 150m≤BP2≤170m.

[0022] The inventors have discovered that smelting tin ash in a short kiln using conventional methods with the addition of anthracite and pig iron filings presents the following problems: 1. Tin ash tailings have a low melting point. Excessive heating causes a sharp decrease in tailings viscosity, leading to the gasification of low-melting-point materials and the formation of foamy slag that overflows the furnace, severely impacting production; 2. Tin ash contains a small amount of sulfur (S), necessitating the addition of pig iron filings. However, iron and tin form a high-melting-point tin-iron alloy that enters the tailings, resulting in a high tin content. Therefore, this invention provides a method for smelting tin ash in a short kiln. Without introducing a new dedicated tin smelting furnace, this method utilizes a short kiln commonly used in the lead smelting industry. Through two different extraction processes—primary and secondary smelting—the remaining tin in the tailings is extracted to the maximum extent, reducing the final tin content to below 1%, essentially reaching the average level of tin smelting without fumigation treatment. This effectively enhances the economic value of the byproducts and has excellent potential for widespread application. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process of the present invention. Implementation

[0024] The method for smelting tin ash in a short kiln according to the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see Figure 1A method for smelting tin ash in a short kiln: one smelting cycle consists of 3-4 primary smeltings followed by 1 secondary smelting. The primary and secondary smelting processes target tin ash and the tailings from tin ash smelting, respectively. This invention, without significantly altering conventional smelting methods, reduces the tin content in the tailings from tin ash smelting by adjusting existing main and auxiliary materials, thereby improving tin recovery and demonstrating good economic benefits. The primary smelting material is tin ash, and the auxiliary materials are anthracite and pig iron filings; the secondary smelting material is the tin ash tailings from the primary smelting; the auxiliary materials are anthracite, limestone, and lead filings. Both primary and secondary smelting are divided into two stages: a lead smelting stage and a slag smelting stage. During lead smelting, the main and auxiliary materials are added, and lead is discharged after smelting. After lead discharge, slag smelting is carried out, and a small amount of residual lead and tailings are discharged after slag smelting.

[0026] First smelting: Lead smelting stage: A certain amount of tin ash, pig iron scraps, and anthracite are added to the short kiln in proportion and ignited. After maintaining a certain natural gas combustion power for a period of time, the lead is discharged. At this time, there is still some tailings in the furnace with a lower temperature and higher lead and tin content.

[0027] Slag refining stage: After the lead is discharged, the smelting continues at a certain natural gas combustion power for a period of time. Then, the remaining small amount of crude lead and tin ash tailings are discharged, and the smelting is completed in one go.

[0028] The lead smelting time and gas power for a single smelting operation are determined by the amount of main raw material added in the single smelting operation, M / t. The lead smelting time / h = 0.10~0.15×M; the gas power / kW = 75~90×M.

[0029] The slag refining time and gas power of a single smelting process are determined by the amount of main raw material added in the single smelting process, M / t. The slag refining time / h = 0.07~0.08×M; the gas power / kW = 70~75×M.

[0030] The tin content (Sn%) of the primary smelting raw material tin ash should be greater than 20%, the antimony content (Sb%) and arsenic content (As%) should be less than 5%, the lead content (Pb%) should be less than 60%, and the sulfur content (S%) should be less than 1.0%.

[0031] The auxiliary materials added in the primary smelting process are calculated based on 100 parts by weight of tin ash (gross weight). 1. Anthracite: Calculated based on the tin ash content of Sn%, Pb%, Sb%, As%, and S%. The calculation method is as follows: Lower limit of anthracite coal addition = 13 × (Sn% + As%) + 3 × Pb% + 7 × Sb% - 40 × S% The upper limit for anthracite coal addition = 16 × (Sn% + As%) + 4 × Pb% + 10 × Sb% - 35 × S.

[0032] 2. Pig iron filings: Calculated specifically based on the sulfur content (S%) of tin ash, using the following method: Addition amount of pig iron filings = 300 × S% + 50%.

[0033] Secondary smelting: Lead smelting stage: After a certain amount (12-16t) of tin ash tailings from the first smelting is collected, it is crushed into blocks of a size suitable for feeding into the short kiln using a crusher. These blocks are then mixed with lead shavings, limestone, and anthracite and fed into the short kiln, where it is ignited. After maintaining a certain natural gas combustion power for a period of time, the lead is discharged.

[0034] Slag refining stage: After the lead is discharged, the smelting continues at a certain natural gas combustion power for a period of time. Then, the remaining small amount of crude lead and tailings are discharged, and the secondary smelting is completed.

[0035] The lead smelting time and gas power in the secondary smelting are determined by the amount of tin ash tailings added in the secondary smelting process (m / t). The lead smelting time / h = 0.13~0.16×m; the gas power / kW = 120~140×m.

[0036] The lead smelting time and gas power in the secondary smelting are determined by the amount of tin ash tailings added in the secondary smelting process (m / t). The smelting time / h = 0.20~0.25×m; the gas power / kW = 150~170×m.

[0037] The tin ash tailings, the main raw material for secondary smelting, generally contain 3% to 8% tin, 2% to 5% lead, and less than 3% sulfur.

[0038] The auxiliary materials for secondary smelting are added in the following proportions based on 100 parts by weight of tin ash tailings: 1. Lead shavings: Add 30-50 parts by weight.

[0039] 2. Anthracite: Calculated based on the Sn% and Pb% content of tin ash and the total secondary smelting time (T / h). The calculation method is as follows: The lower limit for anthracite coal addition = 17 × Sn% + 4 × Pb% + 0.5 × T; The upper limit for anthracite coal addition = 21 × Sn% + 6 × Pb% + 0.7 × T.

[0040] 3. Limestone: Add 3.5 to 5.5 parts by weight.

[0041] The actual amount of main and auxiliary materials added for primary and secondary smelting is based on the capacity of the short kiln, and the material level is based on the material level reaching the lower end of the short kiln feed inlet.

[0042] The following will describe in detail the method for smelting tin ash in a short kiln provided by the present invention through several specific implementation methods. Example 1

[0043] First smelting: Smelting materials: 24.75t tin ash, 1.69t anthracite, and 0.72t pig iron scrap are added to the short kiln.

[0044] Elemental content of tin ash: 23.6% 55.1% 3.3% 0.7% 0.8% Ignite the gas and slowly adjust the natural gas combustion power to 1900kW according to the amount of tin ash added. After about 2.5 hours of smelting, start the lead discharge operation. After the lead discharge is completed, close the lead discharge port and adjust the gas power to 1750kW according to the amount of tin ash added to continue smelting. After 1.8 hours, discharge all the remaining small amount of crude lead and tin ash tailings. The first smelting is completed.

[0045] Second smelting: Smelting materials: 26.83t tin ash, 2.12t anthracite, and 0.70t pig iron scrap are added to the short kiln.

[0046] Elemental content of tin ash: 29.7% 51.2% 2.7% 1.1% 0.7% Ignite the gas and slowly adjust the natural gas combustion power to 2200kW according to the amount of tin ash added. After about 3.0 hours of smelting, perform the lead release operation. After the lead release is completed, close the lead release port and adjust the gas power to 1900kW to continue smelting. After 2.0 hours, release all the remaining small amount of crude lead and tin ash tailings. The second smelting is then completed.

[0047] Third smelting: Smelting materials: 23.90t tin ash, 2.06t anthracite, and 0.48t pig iron scrap are added to the short kiln.

[0048] Elemental content of tin ash: 36.1% 33.3% 3.0% 1.4% 0.5% Ignite the gas and slowly adjust the natural gas combustion power to 2100kW according to the amount of tin ash added. After about 3.0 hours of smelting, start the lead discharge operation. After the lead discharge is completed, close the lead discharge port and adjust the gas power to 1700kW according to the amount of tin ash added to continue smelting. After 1.7 hours, discharge all the remaining small amount of crude lead and tin ash tailings. The third smelting is completed.

[0049] After the first smelting is completed three times, all the tin ash tailings released are collected and their composition is analyzed, totaling 13.30 tons, which will be used as raw material for the second smelting.

[0050] Secondary smelting: Smelting materials: 13.30t tin ash tailings, 0.82t anthracite, 4.17t lead shavings and 0.86t limestone are added to the short kiln.

[0051] Elemental content of tin ash tailings: 7.7% 3.5% 0.3% 0.1% 1.3% Ignition was initiated, and the natural gas combustion power was gradually adjusted to 1700kW based on the amount of tin ash tailings added. After approximately 2.0 hours of smelting, lead was discharged. After lead discharge, the discharge port was sealed, and the gas power was adjusted to 2200kW based on the amount of tin ash tailings added to continue smelting. After 3.0 hours, the remaining small amount of crude lead and tailings were discharged. The discharged tailings were collected and their composition was analyzed, revealing a lead content of 2.38% and a tin content of 0.95%. Example 2

[0052] First smelting: Smelting materials: 25.91t tin ash, 2.18t anthracite, and 0.44t pig iron scrap are added to the short kiln.

[0053] Elemental content of tin ash: 33.4% 41.6% 1.8% 1.9% 0.4% Ignite the gas and slowly adjust the natural gas combustion power to 2000kW according to the amount of tin ash added. After about 3.5 hours of smelting, start the lead discharge operation. After the lead discharge is completed, close the lead discharge port and adjust the gas power to 1800kW according to the amount of tin ash added to continue smelting. After 1.9 hours, discharge all the remaining small amount of crude lead and tin ash tailings. The first smelting is completed.

[0054] Second smelting: Smelting materials: 26.01t tin ash, 1.83t anthracite, and 0.36t pig iron scrap are added to the short kiln.

[0055] Elemental content of tin ash: 25.5% 42.4% 2.4% 2.0% 0.3% Ignite the gas and slowly adjust the natural gas combustion power to 2100kW according to the amount of tin ash added. After about 3.5 hours of smelting, start the lead discharge operation. After the lead discharge is completed, close the lead discharge port and adjust the gas power to 1950kW according to the amount of tin ash added to continue smelting. After 2.0 hours, discharge all the remaining small amount of crude lead and tin ash tailings. The second smelting is completed.

[0056] Third smelting: Smelting materials: 24.37t tin ash, 1.55t anthracite, and 0.78t pig iron scrap are added to the short kiln.

[0057] Elemental content of tin ash: 20.4% 57.8% 4.4% 0.5% 0.9% Ignite the gas and slowly adjust the natural gas combustion power to 2000kW according to the amount of tin ash added. After about 3.5 hours of smelting, start the lead discharge operation. After the lead discharge is completed, seal the lead discharge port and adjust the gas power to 1750kW according to the amount of tin ash added to continue smelting. After 1.8 hours, discharge all the remaining small amount of crude lead and tin ash tailings. The third smelting is completed.

[0058] After the first smelting is completed three times, all the tin ash tailings released are collected and their composition is analyzed, totaling 15.79 tons, which will be used as raw material for the second smelting.

[0059] Secondary smelting: Smelting materials: 15.79t tin ash tailings, 0.88t anthracite, 6.34t lead scrap, and 0.98t limestone are added to the short kiln.

[0060] Elemental content of tin ash tailings: 5.4% 2.9% 0.1% 0.2% 2.4% Ignition was initiated, and the natural gas combustion power was gradually adjusted to 2100kW based on the amount of tin ash tailings added. After approximately 2.5 hours of smelting, lead was discharged. Once lead was discharged, the discharge port was sealed, and the gas power was adjusted to 2500kW to continue smelting, based on the amount of tin ash tailings added. After 3.5 hours, the remaining small amount of crude lead and tailings were discharged. The discharged tailings were collected and their composition was analyzed, revealing a lead content of 3.55% and a tin content of 0.83%.

[0061] Although the method for smelting tin ash in a short kiln provided by the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for smelting tin ash in a short kiln, characterized in that: One smelting cycle consists of three primary smelting processes and one secondary smelting process; The primary smelting process consists of lead smelting stage A and slag smelting stage A. Lead smelting stage A: After adding the primary smelting raw materials to the short kiln in proportion, ignite it; adjust the natural gas power to P1kW according to the amount of main material added, and after smelting for a period of time T1h, carry out the lead discharge operation. At this time, there are still some tailings in the furnace with low temperature and high lead and tin content. Slag Refining Stage A: After lead is discharged in lead smelting stage A, the natural gas combustion power is adjusted to P2kW according to the amount of main material added. After smelting for a period of time T2h, the remaining small amount of crude lead and tin ash tailings are discharged, and the smelting is completed in one go. The primary smelting raw materials include main material one and auxiliary material one; The main material is tin ash; the tin ash contains tin (Sn 1% > 20%), lead (Pb 1% < 60%), sulfur (S 1% < 1%), and the sum of antimony (Sb %) and arsenic (As %) is < 5%; The auxiliary material is anthracite and pig iron filings; The raw materials for the first smelting process are as follows, by mass: Tin gray 100; Cast iron filings C; C = 300 × S% + 50%; Anthracite: 6.83; The raw materials for the second primary smelting are as follows, by mass: Tin gray 100; Cast iron filings C; C = 300 × S% + 50%; Anthracite 7.90; The raw materials for the third primary smelting are as follows, by mass: Tin gray 100; Cast iron filings C; C = 300 × S% + 50%; Anthracite 8.62; The secondary smelting process consists of lead smelting stage B and slag smelting stage B. Lead smelting stage B: Use a crusher to crush the main material 2 into blocks, and then add it together with auxiliary material 2 into the short kiln and ignite it; adjust the natural gas power to BP1kW according to the amount of main material 2 added, and carry out lead discharge operation after smelting for a period of time BT1h. Slag Refining Stage B: After lead is discharged in Lead Refining Stage B, the natural gas power is adjusted to BP2kW according to the amount of main material II added. After smelting for a period of time (BT2h), the remaining small amount of crude lead and tailings are discharged, and the secondary smelting is completed. The raw materials for secondary smelting include main material II and auxiliary material II; The second main material is tin ash tailings released from smelting at least twice; the tin ash tailings contain 3% to 8% tin (Sn2%), 2% to 5% lead (Pb2%), and less than 3% sulfur (S2%). The auxiliary material 2 is limestone, anthracite, and lead shavings; The raw materials for secondary smelting are as follows, by weight: 100 tons of tin ash tailings; 30-50 lead scraps; Limestone 6.47; Anthracite 6.

17.

2. The method for smelting tin ash in a short kiln according to claim 1, characterized in that: The amount of main ingredient added is M tons; 75M≤P1≤90M; 0.10M≤T1≤0.15M.

3. The method for smelting tin ash in a short kiln according to claim 1, characterized in that: The amount of main ingredient added is M tons; 70M≤P2≤75M; 0.07M≤T2≤0.08M.

4. The method for smelting tin ash in a short kiln according to claim 1, characterized in that: The amount of main ingredient 2 added is m tons; 0.13m≤BT1≤0.16m; 120bm≤BP1≤140m.

5. The method for smelting tin ash in a short kiln according to claim 1, characterized in that: The amount of main ingredient 2 added is m tons; 0.2m≤BT2≤0.25bm; 150m≤BP2≤170m.

6. A method for smelting tin ash in a short kiln, characterized in that: One smelting cycle consists of three primary smelting processes and one secondary smelting process; The primary smelting process consists of lead smelting stage A and slag smelting stage A. Lead smelting stage A: After adding the primary smelting raw materials to the short kiln in proportion, ignite it; adjust the natural gas power to P1kW according to the amount of main material added, and after smelting for a period of time T1h, carry out the lead discharge operation. At this time, there are still some tailings in the furnace with low temperature and high lead and tin content. Slag Refining Stage A: After lead is discharged in lead smelting stage A, the natural gas combustion power is adjusted to P2kW according to the amount of main material added. After smelting for a period of time T2h, the remaining small amount of crude lead and tin ash tailings are discharged, and the smelting is completed in one go. The primary smelting raw materials include main material one and auxiliary material one; The main material is tin ash; the tin ash contains tin (Sn 1% > 20%), lead (Pb 1% < 60%), sulfur (S 1% < 1%), and the sum of antimony (Sb %) and arsenic (As %) is < 5%; The auxiliary material is anthracite and pig iron filings; The raw materials for the first smelting process are as follows, by mass: Tin gray 100; Cast iron filings C; C = 300 × S% + 50%; Anthracite 8.41; The raw materials for the second primary smelting are as follows, by mass: Tin gray 100; Cast iron filings C; C = 300 × S% + 50%; Anthracite 7.04; The raw materials for the third primary smelting are as follows, by mass: Tin gray 100; Cast iron filings C; C = 300 × S% + 50%; Anthracite: 6.36; The secondary smelting process consists of lead smelting stage B and slag smelting stage B. Lead smelting stage B: Use a crusher to crush the main material 2 into blocks, and then add it together with auxiliary material 2 into the short kiln and ignite it; adjust the natural gas power to BP1kW according to the amount of main material 2 added, and carry out lead discharge operation after smelting for a period of time BT1h. Slag Refining Stage B: After lead is discharged in Lead Refining Stage B, the natural gas power is adjusted to BP2kW according to the amount of main material II added. After smelting for a period of time (BT2h), the remaining small amount of crude lead and tailings are discharged, and the secondary smelting is completed. The raw materials for secondary smelting include main material II and auxiliary material II; The second main material is tin ash tailings released from smelting at least twice; the tin ash tailings contain 3% to 8% tin (Sn2%), 2% to 5% lead (Pb2%), and less than 3% sulfur (S2%). The auxiliary material 2 is limestone, anthracite, and lead shavings; The raw materials for secondary smelting are as follows, by weight: 100 tons of tin ash tailings; 30-50 lead scraps; Limestone 6.21; Anthracite 5.

57.

7. The method for smelting tin ash in a short kiln according to claim 6, characterized in that: The amount of main ingredient added is M tons; 75M≤P1≤90M; 0.10M≤T1≤0.15M.

8. The method for smelting tin ash in a short kiln according to claim 6, characterized in that: The amount of main ingredient added is M tons; 70M≤P2≤75M; 0.07M≤T2≤0.08M.

9. The method for smelting tin ash in a short kiln according to claim 6, characterized in that: The amount of main ingredient 2 added is m tons; 0.13m≤BT1≤0.16m; 120bm≤BP1≤140m.

10. The method for smelting tin ash in a short kiln according to claim 6, characterized in that: The amount of main ingredient 2 added is m tons; 0.2m≤BT2≤0.25bm; 150m≤BP2≤170m.

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