Method for improving yield of tellurium slag in lead-copper anode slime refining

Abstract

The invention discloses a method for improving the yield of tellurium slag obtained by refining lead-copper anode slime. The method comprises the following steps of: reducing, smelting and separating lead, antimony and arsenic from lead-copper anode slime by using a conventional process to obtain noble lead, putting the noble lead into a refining furnace, discharging surface bonded slag, and then starting to prepare tellurium slag; caustic soda flakes are added in the tellurium slag making process, an oxygen blowing pipe is inserted into the melt for oxygen blowing reaction, and tellurium slag is discharged after tellurium slag making operation is completed, so that alloy is obtained; and the alloy obtained after tellurium slag making is sequentially subjected to oxidation refining secondary slag making and alloy cleaning operation, and after the impurity content in the alloy is lower than the standard requirement, the alloy is discharged out of the furnace to produce an alloy plate. According to the technical scheme, the direct recovery rate of the tellurium slag is remarkably improved, namely the direct recovery rate of the tellurium slag is high. The tellurium slag making process is advanced, so that the problem that a large amount of tellurium is oxidized and enters secondary slag during secondary slag making in the traditional tellurium slag making process is solved, and the direct recovery rate of the tellurium slag is increased by 150%.

Description

1. Technical field:

[0001] The invention belongs to the technical field of rare and precious metal recovery, and in particular relates to a method for improving the yield of tellurium slag in refining lead and copper anode mud. 2. Background technology:

[0002] The production of refined tellurium mainly includes three stages: tellurium enrichment, tellurium separation (i.e., making tellurium slag) and tellurium purification (i.e., wet purification of tellurium to produce refined tellurium). In the third stage of tellurium purification, the technology of each enterprise is not much different. The reason for the large difference in tellurium yield is mainly due to the influence of the first two stages. The following is a detailed introduction to the technology of the first two stages of refined tellurium production.

[0003] First, there are two main methods for tellurium enrichment: 1) using a hydrometallurgical process to treat anode mud for tellurium enrichment; 2) using a pyrometallurgical process to treat anode mud for tellurium enrichment. The first method has a higher tellurium yield, while the second method generally has a lower yield. In particular, for enterprises that use bottom-blowing smelting, the strong oxidizing atmosphere during the smelting process makes the tellurium dispersion more serious.

[0004] Second, there are two main methods for the separation of tellurium: 1) directly making tellurium slag in the alloy; 2) reducing the oxide slag and then making tellurium slag; the first method is the main one, and the second method is the auxiliary one. The main reason is that the process technology for producing tellurium slag from oxide slag is immature, the produced tellurium slag has high impurity content and tellurium grade, and the direct recovery rate of tellurium in the wet purification stage is low. In addition, tellurium is a rare metal. The more times it circulates in the system, the greater the dispersion loss of tellurium. Henan Yuguang Gold and Lead Co., Ltd. uses two methods combined with technology to make tellurium slag. At present, there is no relevant literature publicly reporting "the technology of purely using the second method to make tellurium slag". The first method is used to make tellurium slag, and the tellurium slag making technology is relatively high, and its tellurium output is relatively high.

[0005] Henan Yuguang Gold and Lead Co., Ltd. adopts the bottom blowing smelting process. By refining the bottom blowing smelting process indicators, the tellurium loss in the reduction smelting stage is less than 20%, which is the same as the basic traditional smelting process, but the direct recovery rate of tellurium slag in the refining stage is still low. The direct recovery rate from anode mud to tellurium slag is only about 25%, while domestic companies with better control can reach 40-50%.

[0006] The traditional pyrometallurgical method of making tellurium slag is carried out during the alloy oxidation refining process. The order of alloy oxidation refining is: after the precious lead enters the refining furnace, the sticky slag is first removed (if there is no slag, this step is omitted), then secondary slag is made, followed by tellurium slag, and finally the alloy is removed from the furnace. The tellurium slag makes the silver grade in the alloy about 85%. In this method, most of the tellurium has been oxidized into the secondary slag when making tellurium slag, resulting in a low tellurium slag yield. The main reasons are as follows: The traditional tellurium slag theory is based on the following two properties of tellurium: First, the standard free enthalpy of Bi and Te is 331.1 and 270.3 respectively, with a unit of 298.kJ / Md; second, TeO2+2NaOH=Na2TeO3+H2O. Based on this theory, when the bismuth content in the raw material is much greater than the tellurium content, tellurium will not be oxidized. And only when tellurium is oxidized to TeO2 can it react with NaOH to form Na2TeO3 (the main component of tellurium slag). Therefore, secondary slag must be made first and then tellurium slag. The current tellurium separation technology is: when making tellurium slag, the silver grade in the alloy is about 85% and the tellurium slag temperature is 1050±50℃, resulting in a direct recovery rate of only 40% in the tellurium refining stage.

[0007] From the above existing technologies, it can be seen that finding new ways to improve the separation technology of tellurium is of great significance to improving the direct recovery rate of anode mud tellurium slag, and can also bring higher economic benefits. 3. Summary of the invention:

[0008] The technical problem to be solved by the present invention is: in order to overcome the technical problems existing in the prior art of refined tellurium production, the present invention provides a method for improving the yield of tellurium slag from lead-copper anode mud refining. Compared with the prior art, the technical solution of the present invention can greatly improve the direct recovery rate of tellurium slag, and the direct recovery rate of tellurium slag is increased by 150%; at the same time, the grade of the produced tellurium slag is also high, and the tellurium content in the obtained tellurium slag is ≥20%. .

[0009] In order to solve the above problems, the technical solution adopted by the present invention is:

[0010] The present invention provides a method for improving the yield of tellurium slag from lead-copper anode mud refining, the method comprising the following steps:

[0011] a. The lead-copper anode mud is reduced and smelted by conventional process to separate lead, antimony and arsenic to obtain precious lead, which is placed in a refining furnace to release the sticky slag on the surface, and then tellurium slag is made;

[0012] b. Adjust the flow rate of natural gas entering the refining furnace to make the temperature in the refining furnace reach 950-1050℃. At this time, add caustic soda flakes to start making tellurium slag. After the caustic soda flakes are added, insert an oxygen blowing pipe into the melt to blow oxygen for 10-30 minutes. After the oxygen blowing is completed, pull the oxygen blowing pipe out from under the liquid surface and continue to blow oxygen on the surface for 60-90 minutes. After the tellurium slag making operation is completed, release the tellurium slag to obtain the alloy;

[0013] c. The alloy obtained in step b is subjected to oxidation refining in sequence to produce secondary slag and clean alloy. When the impurity content in the alloy is lower than the standard requirement, the alloy plate is produced by taking out of the furnace.

[0014] According to the above method for improving the yield of tellurium slag in refining lead-copper anode mud, the antimony content in the precious lead in step a is less than 3%.

[0015] According to the above method for improving the tellurium slag yield of lead-copper anode mud refining, the amount of caustic soda added in step b is 2 to 4 times the weight of tellurium metal in the precious lead.

[0016] According to the above method for improving the tellurium slag yield of lead-copper anode mud refining, in step b, when the tellurium content in the obtained alloy is detected to be ≤0.5%, the tellurium slag making operation is completed.

[0017] According to the above method for improving the tellurium slag yield of lead-copper anode mud refining, the medium for blowing oxygen through the oxygen blowing tube in step b is pure oxygen or compressed air; the tellurium content in the obtained tellurium slag is ≥20%.

[0018] According to the above method for improving the tellurium slag yield of lead-copper anode mud refining, the time for making tellurium slag each time in step b is controlled to be 1 to 3 hours (preferably 2 hours).

[0019] According to the above method for improving the tellurium slag yield of lead-copper anode mud refining, the specific operation process of oxidation refining to make secondary slag and clean alloy in step c is:

[0020] Passing oxygen or compressed air into the alloy obtained after making tellurium slag, adopting the method of blowing oxygen underwater or blowing oxygen on the surface to make secondary slag, adjusting the amount of natural gas in the burner during making secondary slag, so that the furnace temperature is controlled at 850-950°C, and stopping blowing oxygen after reacting for 2 hours; then increasing the amount of natural gas to raise the furnace temperature to 900-1000°C for secondary slag discharge; repeating the secondary slag making operation according to this method until the alloy grade detected by sampling reaches 95±2%, and the secondary slag making operation is completed;

[0021] Then prepare for the alloy cleaning operation. Turn off the fire before cleaning the alloy. Add a mixture of sodium nitrate and soda ash into the furnace, stirring while adding. After the auxiliary materials are added, react for 10 to 30 minutes, then continue to increase the furnace temperature to 1100 to 1250°C, and insert the oxygen blowing tube into the liquid to blow oxygen for 2 hours, then stop blowing oxygen and let it settle for 20 to 30 minutes, release the alloy slag, and repeat the alloy cleaning operation in this way until the alloy grade meets the standard when sampled and tested. The alloy cleaning operation is completed and the alloy plate is produced from the furnace.

[0022] According to the above-mentioned method for improving the yield of tellurium slag in refining lead and copper anode mud, the mass ratio of sodium nitrate to soda ash in the mixture of sodium nitrate and soda ash is 3 to 4:1.

[0023] According to the above method for improving the tellurium slag yield of lead-copper anode mud refining, the total content of gold and silver in the obtained alloy plate is greater than 98wt%, copper is less than 1wt%, bismuth is less than 0.3wt%, and tellurium is less than 0.15wt%.

[0024] During the alloy cleaning process, when the surface of the metal sample is smooth and flat and appears pure silver-white, the sample is difficult to break. After breaking, the cross section is duck egg white in color with a small condensation groove in the middle, meeting the furnace standards.

[0025] The positive beneficial effects of the present invention are:

[0026] 1. The present invention advances the alloy tellurium slag to before the secondary slag is made, reducing the tellurium dispersion loss in the alloy refining process; the principle is based on the property of tellurium: 3Te+6NaOH=2Na2Te+Na2TeO3+3H2O. According to the property of tellurium, the tellurium slag is not limited by the Bi and Te content in the raw materials. Te does not need to be oxidized first, and can be directly converted from a single substance to Na2TeO3 and Na2Te, wherein Na2Te can float on the melt surface and separate from the precious metal alloy at a temperature higher than 953°C. Therefore, the tellurium slag making process is advanced.

[0027] 2. The present invention adds new conditions in the process of making tellurium slag: oxygen blowing is adopted in the process of making tellurium slag. On the one hand, the stirring of the alloy is strengthened to fully mix the tellurium in the caustic soda flakes and the alloy. On the other hand, by supplementing oxygen, the Na2Te floating on the surface of the alloy melt is further oxidized into Na2TeO3 to form tellurium slag. Controlling the amount of oxygen supplementation can ensure that the bismuth is oxidized very little while the tellurium slag is produced, thereby ensuring the tellurium grade of the tellurium slag.

[0028] 3. The technical solution of the present invention significantly improves the direct recovery rate of tellurium slag (i.e., the direct recovery rate of tellurium slag is high): since the tellurium slag making process is advanced, the problem of tellurium being oxidized in large quantities and entering into secondary slag during the traditional tellurium slag making process is reduced, and the direct recovery rate of tellurium slag is increased by 150%.

[0029] 4. The technical solution of the present invention has high slag making efficiency: since the process of making tellurium slag adopts oxygen blowing and stirring, the reaction progress is accelerated and the time of single tellurium slag making is shortened. The tellurium content of tellurium slag is high, and the tellurium content in the tellurium slag is ≥20%. 4. Specific implementation methods:

[0030] The present invention is further described below in conjunction with embodiments, but the protection scope of the technical solution of the present invention is not limited thereto.

[0031] Embodiment 1:

[0032] The method for improving the yield of tellurium slag from lead-copper anode mud refining of the present invention has the following detailed operation steps:

[0033] a. Precious lead is obtained by reducing and smelting lead-copper anode mud to separate lead, antimony and arsenic through conventional process. The obtained precious lead is placed in a refining furnace, and the surface sticky slag is released. The temperature in the furnace is controlled to be 1000±2℃. When the smoke in the furnace is small, tellurium slag is made. At this time, the precious lead contains 1.5% antimony and 2.54% tellurium. The total amount of precious lead is about 15 tons, and the amount of tellurium metal is about 381kg.

[0034] b. Adjust the flow rate of natural gas entering the refining furnace to keep the temperature in the refining furnace at 1000±2℃. At this time, add 200kg of caustic soda flakes to start making tellurium slag (using rakes to stir during the process of adding caustic soda flakes). After the caustic soda flakes are added, insert an oxygen blowing pipe into the melt to blow oxygen (pure oxygen is used as the oxygen blowing medium). The oxygen blowing time is 25min (the thickness of the liquid caustic soda in the furnace is 1.9cm at this time). After the oxygen blowing is completed, pull the oxygen blowing pipe out from below the liquid surface, and continue to blow oxygen on the surface for 90min; after the reaction is completed, release the tellurium slag; according to this method and the amount of auxiliary materials added, tellurium slag is made 7 times in total, the output of tellurium slag is 1.7 tons, the amount of caustic soda flakes used is 1400kg, the amount of caustic soda flakes used / tellurium metal amount is 3.55, and the alloy is obtained after the tellurium slag is made; sampling and testing after the tellurium slag is made, the alloy contains 0.3% tellurium, and the tellurium slag contains 20.9% tellurium;

[0035] c. After the tellurium slag is made, oxygen is introduced and the secondary slag making operation is carried out by blowing oxygen under liquid. The natural gas volume of the burner is adjusted to control the furnace temperature to 850-950°C. The oxygen blowing is stopped after the reaction for 2 hours. Then the natural gas volume is increased to raise the furnace temperature to 900-1000°C for the secondary slag discharge operation. The secondary slag making operation is repeated according to this method until the alloy grade reaches 95% after sampling and observation. The secondary slag making operation is completed, and a total of 7 tons of secondary slag is discharged during the period.

[0036] Then prepare for the alloy cleaning operation. Turn off the fire before cleaning the alloy. Mix 37.5kg of sodium nitrate and 12.5kg of soda ash evenly and add them into the furnace, stirring while adding. After the auxiliary materials are added, react for 30 minutes, then continue to increase the furnace temperature to 1100-1250℃, and insert the oxygen blowing pipe into the liquid to blow oxygen for 2 hours, then stop blowing oxygen and let it stand for 30 minutes, release the alloy slag, and repeat the alloy cleaning operation according to this method until sampling and observing the alloy grade. When the surface of the metal sample is smooth and flat and is pure silver white, the sample is difficult to break. After breaking, the cross section is duck egg white with a small condensation groove in the middle, which meets the furnace discharge standard. 9.66 tons of alloy plates were obtained. After inspection, the gold + silver content of the alloy plates was 98.5wt%, the copper content was 0.43wt%, the bismuth content was 0.08wt%, and the tellurium content was <0.008wt%.

[0037] Embodiment 2:

[0038] The method for improving the yield of tellurium slag from lead-copper anode mud refining of the present invention has the following detailed operation steps:

[0039] a. Precious lead is obtained by reducing and smelting lead-copper anode mud to separate lead, antimony and arsenic through conventional process. The obtained precious lead is placed in a refining furnace, and the surface sticky slag is released. The temperature in the furnace is controlled to be 1000±2℃. When the smoke in the furnace is small, tellurium slag is made. At this time, the precious lead contains 2.3% antimony and 4.8% tellurium. The total amount of precious lead is about 12 tons, and the amount of tellurium metal is about 576kg.

[0040] b. Adjust the flow rate of natural gas entering the refining furnace to keep the temperature in the refining furnace at 1000±2℃. At this time, add 200kg of caustic soda flakes to start making tellurium slag (during the process of adding caustic soda flakes, stir with the gas blown out by the oxygen blowing pipe). After the caustic soda flakes are added, insert the oxygen blowing pipe into the melt to blow oxygen (the oxygen blowing medium is pure oxygen). The oxygen blowing time is 25min (the thickness of the liquid caustic soda in the furnace is 2.3cm at this time). After the oxygen blowing is completed, pull out the oxygen blowing pipe from below the liquid surface, and continue to blow oxygen on the surface for 90min; after the reaction is completed, release the tellurium slag; according to this method and the amount of auxiliary materials added, tellurium slag is made 7 times in total, the output of tellurium slag is 1.9 tons, the amount of caustic soda flakes used is 1400kg, the amount of caustic soda flakes used / tellurium metal amount is 2.4, and the alloy is obtained after the tellurium slag is made; sampling and testing after the tellurium slag is made, the alloy contains 0.5% tellurium, and the tellurium slag contains 27.2% tellurium;

[0041] c. After the tellurium slag is made, oxygen is introduced and the secondary slag making operation is carried out by blowing oxygen under liquid. The natural gas volume of the burner is adjusted to control the furnace temperature to 850-950°C. After reacting for 2 hours, the oxygen blowing is stopped. Then the natural gas volume is increased to raise the furnace temperature to 900-1000°C for the secondary slag discharge operation. The secondary slag making operation is repeated according to this method until the alloy grade reaches 96% after sampling and observation. The secondary slag making operation is completed, and a total of 7 tons of secondary slag is discharged during the period.

[0042] Then prepare for the alloy cleaning operation. Turn off the fire before cleaning the alloy. Mix 37.5kg of sodium nitrate and 12.5kg of soda ash evenly and add them into the furnace, stirring while adding. After the auxiliary materials are added, react for 30 minutes, then continue to increase the furnace temperature to 1100-1250℃, and insert the oxygen blowing pipe into the liquid to blow oxygen for 2 hours, then stop blowing oxygen and let it stand for 30 minutes, release the alloy slag, and repeat the alloy cleaning operation according to this method until sampling and observing the alloy grade. When the surface of the metal sample is smooth and flat and is pure silver white, the sample is difficult to break. After breaking, the cross section is duck egg white with a small condensation groove in the middle, which meets the furnace discharge standard. 4.66 tons of alloy plates are obtained. After inspection, the gold + silver content of the alloy plates is 98.7wt%, the copper content is 0.53wt%, the bismuth content is 0.15wt%, and the tellurium content is <0.009wt%.

Claims

1. A method for improving the yield of tellurium slag from lead-copper anode mud refining, characterized in that: The method comprises the following steps: a. The lead-copper anode mud is reduced and smelted by conventional process to separate lead, antimony and arsenic to obtain precious lead, which is placed in a refining furnace to release the sticky slag on the surface, and then tellurium slag is made; b. Adjust the flow rate of natural gas entering the refining furnace to make the temperature in the refining furnace reach 950-1050℃. At this time, add caustic soda flakes to start making tellurium slag. After the caustic soda flakes are added, insert an oxygen blowing pipe into the melt to blow oxygen for 10-30 minutes. After the oxygen blowing is completed, pull the oxygen blowing pipe out from under the liquid surface and continue to blow oxygen on the surface for 60-90 minutes. After the tellurium slag making operation is completed, release the tellurium slag to obtain the alloy; c. The alloy obtained in step b is subjected to oxidation refining in sequence to produce secondary slag and clean alloy. When the impurity content in the alloy is lower than the standard requirement, the alloy plate is produced by taking out of the furnace.

2. The method for improving the tellurium slag yield of lead-copper anode mud refining according to claim 1, characterized in that: The antimony content in the precious lead described in step a is less than 3%.

3. The method for improving the tellurium slag yield of lead-copper anode mud refining according to claim 1, characterized in that: The amount of caustic soda added in step b is 2 to 4 times the weight of tellurium metal in the precious lead.

4. The method for improving the tellurium slag yield of lead-copper anode mud refining according to claim 1, characterized in that: In step b, when the tellurium content in the obtained alloy is detected to be ≤0.5%, the tellurium slag making operation is completed.

5. The method for improving the tellurium slag yield of lead-copper anode mud refining according to claim 1, characterized in that: In step b, the medium for blowing oxygen through the oxygen blowing pipe is pure oxygen or compressed air; the tellurium content in the obtained tellurium slag is ≥20%.

6. The method for improving the tellurium slag yield of lead-copper anode mud refining according to claim 1, characterized in that: In step b, the time for making tellurium slag each time is controlled to be 1 to 3 hours.

7. The method for improving the tellurium slag yield from lead-copper anode mud refining according to claim 1, characterized in that: The specific operation process of oxidation refining to make secondary slag and clean alloy in step c is: Passing oxygen or compressed air into the alloy obtained after making tellurium slag, adopting the method of blowing oxygen underwater or blowing oxygen on the surface to make secondary slag, adjusting the amount of natural gas in the burner during making secondary slag, so that the furnace temperature is controlled at 850-950°C, and stopping blowing oxygen after reacting for 2 hours; then increasing the amount of natural gas to raise the furnace temperature to 900-1000°C for secondary slag discharge; repeating the secondary slag making operation according to this method until the alloy grade detected by sampling reaches 95±2%, and the secondary slag making operation is completed; Then prepare for the alloy cleaning operation. Turn off the fire before cleaning the alloy. Add a mixture of sodium nitrate and soda ash into the furnace, stirring while adding. After the auxiliary materials are added, react for 10 to 30 minutes, then continue to increase the furnace temperature to 1100 to 1250°C, and insert the oxygen blowing tube into the liquid to blow oxygen for 2 hours, then stop blowing oxygen and let it settle for 20 to 30 minutes, release the alloy slag, and repeat the alloy cleaning operation in this way until the alloy grade meets the standard when sampled and tested. The alloy cleaning operation is completed and the alloy plate is produced from the furnace.

8. The method for improving the tellurium slag yield from lead-copper anode mud refining according to claim 7, characterized in that: The mass ratio of sodium nitrate to soda ash in the mixture of sodium nitrate and soda ash is 3 to 4:

1.

9. The method for improving the tellurium slag yield from lead-copper anode mud refining according to claim 7, characterized in that: The total content of gold and silver in the obtained alloy plate is greater than 98wt%, copper is less than 1wt%, bismuth is less than 0.3wt%, and tellurium is less than 0.15wt%.