CN1041441C - Process for removing Pb and Zn from raw Bi - Google Patents
Process for removing Pb and Zn from raw Bi Download PDFInfo
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- CN1041441C CN1041441C CN94112677A CN94112677A CN1041441C CN 1041441 C CN1041441 C CN 1041441C CN 94112677 A CN94112677 A CN 94112677A CN 94112677 A CN94112677 A CN 94112677A CN 1041441 C CN1041441 C CN 1041441C
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Abstract
The present invention relates to a process for removing lead and zinc from raw bismuth, and comprises the following steps: adding phosphoric acid or phosphorus oxide to molten bismuth in the process of raw bismuth fire refining at a certain operation temperature, carrying out the reaction of lead-zinc impurities and phosphorus in the molten bismuth firstly for generating lead-zinc metaphosphate floating on the surface of the molten bismuth, and removing the lead-zinc metaphosphate. The operation temperature is from 290 to 500 DEG C, and the quantity of the adding phosphorus is at least equal to the sum of 1.4 to 1.8 times of lead content and 2.6 to 3.2 times of zinc content in the raw bismuth. After separation for at least two times, the raw bismuth with lead of 5 to 10% and zinc of 2% can be refined to be bismuth metal with lead content of less than 0.001% and zinc content of less than 0.005%. The process has the characteristics of simple technology, low cost and high recovery rate.
Description
The invention relates to a method for removing lead and zinc from crude bismuth, belongs to the technical field of pyrometallurgy of nonferrous metals, is suitable for the refining and impurity removal process of bismuth, and can achieve the effect of refining crude bismuth into refined bismuth with low cost and high recovery rate.
Bismuth is a rare metal, and is mostly symbiotic with lead, tungsten and molybdenum deposits in the nature, and crude bismuth obtained in the process of refining main metals and subsequent comprehensive recovery of ores or concentrates often contains a large amount of arsenic, antimony, copper, silver, lead and other impurities, and must be further refined to have application value.
Bismuth refining is generally performed by two methods, namely electrolytic refining and fire refining, and in recent years, the fire process tends to replace the electrolytic process. The traditional fire refining process comprises the following steps: oxidizing and refining to remove arsenic and antimony; liquating and adding sulfur to remove copper; adding zinc to remove silver; finally, refined bismuth with high purity is obtained by chlorination refining to remove lead and zinc.
At present, the traditional method for removing lead and zinc in bismuth smelting factories at home and abroad is a chlorination refining method, namely chlorine gas is introduced into molten bismuth liquidat a certain temperature, and zinc and lead are successively superior to bismuth by virtue of the difference of free enthalpy of bismuth and lead zinc chloride to generate chloride which is then chlorinated to enter slag (Wangli's editor' bismuth metallurgy, metallurgical industry Press, 1986). This conventional method has the following disadvantages in practice: (1) the reaction is a gas-liquid reaction, and the reaction speed is limited by the contact area of chlorine and bismuth liquid, so the impurity removal time is longer, particularly in the later stage of lead removal, the concentration of lead in the bismuth liquid is reduced, the diffusion speed is slowed, and the impurity removal is not facilitated as soon as possible. (2) Impurities such as chlorine and the like are remained after the bismuth liquid is refined, and further alkaline refining is needed, so that a product meeting the requirements can be obtained. (3) Chlorine is extremely toxic and corrosive gas, the leaked or escaped unreacted chlorine can harm human bodies and pollute the operating environment, the chlorine severely corrodes equipment at high temperature, and leakage accidents of the smelting pot sometimes occur. (4) The refining slag contains high bismuth, the later-period slag contains 3-5% of bismuth, and the direct refining yield is reduced.
In 1973, k.d. thomson proposed adsorption removal of lead from metallic bismuth by silica gel (american atomic energy commission reported IST594.1973), which passed bismuth liquid through a silica gel column at a certain temperature, where the bismuth liquid contained lead in a range of 0.016 to 0.10% and could be removed to a high purity range of 0.0005% or less, but the silica gel had a low adsorption capacity for lead, and no suitable regeneration method was available for the silica gel after adsorption, and thus it was not industrially applicable.
The invention aims to overcome the defects in the background technology, and the method for removing lead and zinc has the advantages of simple process, convenient operation, low cost and high recovery rate by selecting more appropriate additives and putting the additives into the metal bismuth liquid at a certain operation temperature to remove lead and zinc impurities in scum.
The invention provides a method for removing lead and zinc from crude bismuth, wherein the selected additive is phosphoric acid or phosphorus oxide, phosphoric acid or phosphorus oxide in metal bismuth liquid is added under micro-oxidation atmosphere, and reacts with lead and zinc in bismuth liquid at a certain operation temperature to generate metaphosphate, and the generated temperature is different due to different stability of zinc salt, lead salt and bismuth salt, so that the additive added at the selected temperature can preferentially react with lead and zinc to generate lead metaphosphate and zinc metaphosphate which floats on the surface of bismuth liquid to be removed, and the reaction formula is as follows:
generated Bi (PO)3)3Then the lead-zinc alloy and the lead-zinc in the bismuth liquid are subjected to a displacement reaction, and the reaction formula is as follows:
therefore, the slag produced in the later refining still has certain lead and zinc removal effect after being returned to the former refining.
The technical scheme of the invention will be explained with reference to the accompanying drawings. The attached drawing is a process flow chart of crude bismuth fire refining. The dotted line part is the original working procedure, and the solid line part is the new lead and zinc removing method provided by the invention. As can be seen, after crude bismuth obtained by wet or pyrogenic smelting is subjected to arsenic and antimony removal by oxidation, liquation, copper removal by adding sulfur and silver removal by adding zinc, lead and zinc removal by adding phosphoric acid or phosphorus oxide is started. Wherein the operation temperature is 290 ℃ and 500 ℃, such as adding liquid phosphoric acid; mechanically stirring for 1-2 hr after dewatering, taking out the residue on the surface of bismuth liquid, adding additive for the second time until the lead and zinc contents of bismuth are respectively below 0.001% and 0.0005%, the adding amount of phosphoric acid or phosphorus oxide depends on the lead and zinc contents in crude bismuth, and phosphoric acid depends on P contained in crude bismuth2O5Measured in P2O5It is calculated that the additive should be added at least equal to the sum (wt%) of 1.4-1.8 times the lead content and 2.6-3.2 times the zinc content of the bismuth crude.
The actual multiple required for lead and zinc removal is related to the initial impurity concentration of the raw materials, the refining depth of the final product and the degree of strict operation.
The operation temperature is controlled to be 370 ℃ and 400 ℃, the effect is optimal, and the excessive high temperature can cause P2O5Volatilization loss is reduced, and the dosage of the additive is increased; the reaction speed is slowed down due to low reaction speed, and the operation time is prolonged. Afterstirring for I-2 hours at the recommended temperature, the concentration of lead and zinc in the two phases of the bismuth liquid and the slag is close to an equilibrium state, and if the reaction time is further prolonged, the impurity removal effect cannot be obviously improved.
The phosphoric acid or the oxide of the phosphorus added according to the lead and zinc content in the crude bismuth can be added for at least two times, wherein the scum obtained by later-stage addition can be returned to the earlier stage for recycling, because the later-stage scum contains unreacted free P2O5Or the bismuth metaphosphate generated by the reaction returns to the earlier stageThe lead and zinc removing effect is still utilized, the additive consumption can be saved, and the loss of bismuth in the slag is reduced.
The early-stage slag is white at the recommended operating temperature and contains a little bismuth beads, the melting point of the early-stage slag is about 450-3 -60% (wt%).
The impurity content of the metal bismuth obtained after refining is Pb<0.001%, Zn<0.0005% (weight%), and it is worth mentioning that the phosphorus element does not enter the metal bismuth after smelting, and is limited by the detection sensitivity, and the metal bismuth obtained in the invention contains P<0.0002%.
Examples
Example (1):
2214g of crude bismuth after adding zinc and removing silver, which contains 4.47 percent of Pb2 and 2.21 percent of Zno, is placed in an iron pot, the temperature is maintained at 380-3PO470 percent of industrial phosphoric acid 250ml, stirring for 1 hour and 20 minutes after dehydration, adding 100ml of phosphoric acid (the concentration is the same as the above) and stirring for 1 hour and 30 minutes after slag removal, wherein the bismuth liquid after slag removal contains Pb3.72 percent and Zn0.0048 percent (weight percent), adding 35ml of phosphoric acid (the concentration is the same as the above) for the third time and stirring for 1 hour and 30 minutes, the bismuth liquid after slag removal contains Pb0.0006 percent, Zn0.00019 percent and P less than 0.0002 percent (weight percent), the weight of refined bismuth is 1981.5g, the direct yield is 96.17 percent, and the total weight of the three times of refined slag is 497 g.
Example (2)
1146g of crude bismuth containing 5.07% of Pb2.04% (wt%) was put into 45g of the third slag obtained under the conditions of example (1), and stirred at 380 ℃ and 400 ℃ for 1 hour to obtain 48g of slag, wherein the bismuth solution contained 4.88% of pb and 1.62% (wt%) of Zn1.62%. Fully indicates that the later-stage slag returns to the early-stage refining process and still has the effect of removing lead and zinc.
Example (3):
example (1) Total weight of slag 497g produced in the refining process was placed in an iron kettle and maintained at 480 ℃ 500-Melting, stirring slightly, standing for 30 minutes, recovering 60g of metal bismuth containing 0.14% of Pb0.03% and 430g of slag containing 0.74% of Bi0.89%, 21.89% of Pb11.51% of Zno, and recycling PO3 -60 percent (calculated by the weight percent). The overall recovery of the refining process of example (1) was 99.08%.
Claims (3)
1. A method for removing lead and zinc from crude bismuth, namely, in the fire refining process of bismuth, lead and zinc enter into scum to be removed by adding additives, and is characterized in that the added additives are phosphoric acid or oxides of phosphorus, wherein the operation temperature is 290-500 ℃, and the phosphoric acid or oxides of phosphorus
With P2O5The calculated input amount is at least equal to the sum (weight percent) of 1.4-1.8 times of the lead content and 2.6-3.2 times of the zinc content in the crude bismuth.
2. The method for removing Pb and Zn from crude bismuth according to claim 1, wherein the operating temperature is controlled to 370-400 ℃.
3. The method according to claim 1 or 2, wherein the phosphoric acid or the oxide of phosphorus added according to the content of lead and zinc in the crude bismuth is added in at least two times, and wherein the dross obtained by the late addition is returned to the early stage for reuse.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94112677A CN1041441C (en) | 1994-12-15 | 1994-12-15 | Process for removing Pb and Zn from raw Bi |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94112677A CN1041441C (en) | 1994-12-15 | 1994-12-15 | Process for removing Pb and Zn from raw Bi |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1124783A CN1124783A (en) | 1996-06-19 |
| CN1041441C true CN1041441C (en) | 1998-12-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN94112677A Expired - Fee Related CN1041441C (en) | 1994-12-15 | 1994-12-15 | Process for removing Pb and Zn from raw Bi |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100413984C (en) * | 2006-09-26 | 2008-08-27 | 郴州市三和有色金属有限公司 | Impurity removing refining process of high pure bismuth |
| CN101928842A (en) * | 2010-09-27 | 2010-12-29 | 娄底市兴华有色金属有限公司 | Lead removing agent for use in stibium pyrorefining and lead removing method thereof |
| CN102634681A (en) * | 2012-05-15 | 2012-08-15 | 谈应顺 | Deleading agent and deleading method for fire refining of bismuth |
| CN110791666A (en) * | 2019-12-18 | 2020-02-14 | 益阳生力材料科技股份有限公司 | Bismuth removing agent for antimony smelting and refining |
| CN115961152A (en) * | 2022-12-02 | 2023-04-14 | 中南大学 | Preparation method of high-purity metal bismuth |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU897880A1 (en) * | 1980-03-28 | 1982-01-15 | Институт химии Дальневосточного научного центра АН СССР | Method of processing bismuth-containing sulfide industrial products |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU897880A1 (en) * | 1980-03-28 | 1982-01-15 | Институт химии Дальневосточного научного центра АН СССР | Method of processing bismuth-containing sulfide industrial products |
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| CN1124783A (en) | 1996-06-19 |
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