A method for preparing lead sulphide from complex lead sulphide ores

Abstract

The application provides a method for preparing lead sulfide from a complex lead sulfide ore, and belongs to the technical field of lead sulfide preparation. The complex lead sulfide ore is subjected to vacuum distillation to obtain crude lead sulfide; the temperature of the vacuum distillation is 700-1200 DEG C, the time is 30-120 min, and the vacuum degree is 1-10 Pa; the crude lead sulfide is mixed with an alkaline solution to perform alkaline leaching, solid-liquid separation, and then lead sulfide pure product is obtained. In the application, the temperature and heating time are controlled under vacuum conditions, the structure of the solid solution in the original mineral is broken, the lead sulfide is volatilized alone, preliminary separation is realized, and then the lead sulfide with high purity is obtained through the wet leaching method. The examples show that the purity of the lead sulfide obtained through the vacuum distillation-alkaline solution leaching method is 90-98%, the Sb content is 0.5-3%, the lead sulfide has high purity, and the lead sulfide is directly obtained from the complex lead sulfide ore.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lead sulfide preparation, and particularly relates to a method for preparing lead sulfide from a complex lead sulfide ore. BACKGROUND

[0002] Lead sulfide (PbS) has unique optical and electrical properties due to its small energy band gap (0.41 eV, 300K) and large exciton radius (18 nm), and is widely used in infrared detectors, photoelectrochemical electrodes, and other optoelectronic devices, as well as solar cells. In addition, due to the significant third-order nonlinear optical properties of PbS particles (30 times that of GaAs and more than 1000 times that of CdS), it is expected to have a wide application prospect in high-speed optical switches.

[0003] In the prior art, the methods for preparing lead sulfide mainly include the following: one is to directly combine lead and sulfur to generate lead sulfide, but this method requires high-purity sulfur and lead, increasing the cost; another is to react sulfur compounds and lead compounds, including hydrothermal method, solvothermal method, electron beam irradiation method, ultrasonic chemical method, and microwave method, which need surfactants, organic reaction media, and other control conditions for synthesis, and the process is complex, the energy consumption is high, and the requirements for experimental materials and environment are also very high; the third is to obtain lead sulfide from brittle sulfide antimony ore concentrate through vacuum decomposition-grading condensation or vacuum thermal decomposition-vacuum distillation, as published in the paper "Experimental Study on Separation of Lead Sulfide and Antimony Sulfide from Brittle Sulfide Antimony Ore by Vacuum Distillation" by Zhou Zheng'en (Kunming University of Science and Technology, April 2019). However, whether it is vacuum decomposition-grading condensation or vacuum thermal decomposition-vacuum distillation, the final product obtained is lead sulfide and antimony sulfide, and the ore used is single. China is a large producer of lead, and most of the existing lead ore is associated ore or refractory ore, which has low utilization rate. Therefore, it is of great significance to improve the utilization rate of lead ore and directly obtain lead sulfide (PbS). SUMMARY

[0004] Therefore, the purpose of the present application is to provide a method for preparing lead sulfide from a complex lead sulfide ore. The method provided by the present application has low energy consumption, can obtain lead sulfide with high purity, improves the utilization rate of complex ore, and promotes the industrial production of lead sulfide.

[0005] In order to solve the above technical problems, the present application provides the following technical solutions:

[0006] The present application provides a method for preparing lead sulfide from a complex lead sulfide ore, comprising the following steps:

[0007] The complex lead sulfide ore is vacuum distilled to obtain crude lead sulfide; the temperature of the vacuum distillation is 700-1200℃, the time is 30-120min, and the vacuum degree is 1-10Pa;

[0008] The crude lead sulfide is mixed with an alkaline solution to perform alkaline leaching, and solid-liquid separation is performed to obtain pure lead sulfide.

[0009] Preferably, the temperature rising procedure of the vacuum distillation comprises: placing the complex lead sulfide ore in a vacuum furnace, opening the circulating water, starting vacuum pumping with a vacuum pump, waiting until the vacuum degree is reduced to 10-30Pa, starting first temperature rising, waiting until the first temperature rising is to 200-300℃, performing second temperature rising, and controlling the furnace pressure to 1-10Pa to perform second temperature rising to the temperature of the vacuum distillation; the first temperature rising rate is 18-20℃ / min; and the second temperature rising rate is 20-30℃ / min.

[0010] Preferably, the alkaline substance in the alkaline solution is NaOH and Na2S, the concentration of Na2S in the alkaline solution is 100-140g / L, and the concentration of NaOH is 20-50g / L.

[0011] Preferably, the solid-liquid ratio of the crude lead sulfide to the alkaline solution is 1g:2-5mL.

[0012] Preferably, the temperature of the alkaline leaching is 60-100℃, and the time is 30-120min.

[0013] Preferably, the alkaline leaching is performed under stirring, and the stirring speed is 500-2000rpm.

[0014] Preferably, before the alkaline leaching, the mixture of the crude lead sulfide and the alkaline solution is further slurryized, and the slurryizing time is 10-20min.

[0015] Preferably, the lead content in the complex lead sulfide ore is 25-30wt%.

[0016] Preferably, the complex lead sulfide ore comprises lead sulfide, antimony sulfide and iron sulfide; the antimony sulfide, the iron sulfide and part of the lead sulfide are embedded together in the form of a solid solution, and the remaining lead sulfide exists independently.

[0017] Preferably, before the vacuum distillation, the complex lead sulfide ore is further subjected to grinding and briquetting in sequence, and the briquetting forming pressure is 5-8MPa.

[0018] The application provides a method for preparing lead sulfide from complex lead sulfide ore, comprising the following steps: vacuum distillation of the complex lead sulfide ore to obtain crude lead sulfide; the temperature of the vacuum distillation is 700-1200 DEG C, the time is 30-120 min, and the vacuum degree is 1-10 Pa; alkali leaching of the crude lead sulfide by mixing with an alkaline solution, solid-liquid separation, and obtaining of pure lead sulfide.

[0019] The results of the examples show that the purity of the lead sulfide obtained by the method of vacuum distillation-alkaline solution leaching is 90-98%, and the Sb content is 0.5-3 wt%, which shows that the purity of the lead sulfide obtained by the method is high, and the lead sulfide product is directly obtained from the complex lead sulfide ore. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0021] Figure 1 The flowchart of the method for preparing lead sulfide according to the application is shown in the figure. DETAILED DESCRIPTION

[0022] The application provides a method for preparing lead sulfide from complex lead sulfide ore, comprising the following steps:

[0023] Vacuum distillation of the complex lead sulfide ore to obtain crude lead sulfide; the temperature of the vacuum distillation is 700-1200 DEG C, the time is 30-120 min, and the vacuum degree is 1-10 Pa;

[0024] Alkali leaching of the crude lead sulfide by mixing with an alkaline solution, solid-liquid separation, and obtaining of pure lead sulfide.

[0025] In the application, the raw materials used are all commercially available goods well known in the art, unless otherwise specified.

[0026] The application performs vacuum distillation on the complex lead sulfide ore to obtain crude lead sulfide.

[0027] In the present application, the complex lead sulfide ore belongs to complex and refractory polymetallic sulfide ore, and the main components are Pb4Sb6FeS 14 , PbS, ZnS and FeS, the intergrowth relationship of metal minerals is complex, lead and antimony are wrapped each other, and zinc and iron are fixed together. The metal content is high, and the lead content is the highest, about 30% of the raw ore, and the gangue mineral content is low.

[0028] In the present application, the lead content in the complex lead sulfide ore is preferably 25-30 wt%, more preferably 26-28 wt%.

[0029] In the present application, the lead in the complex lead sulfide ore exists in the form of lead sulfide.

[0030] From the mineral composition, the complex lead sulfide ore preferably includes lead sulfide, antimony sulfide and iron sulfide; the antimony sulfide, iron sulfide and part of the lead sulfide are embedded together in the form of solid solution, and the remaining lead sulfide exists independently. In the present application, the complex lead sulfide ore inevitably contains Zn, Si and Sn impurity elements.

[0031] Before the vacuum distillation, the present application preferably sequentially performs grinding and briquetting on the complex lead sulfide ore, and the forming pressure of the briquetting is preferably 5-8 MPa, more preferably 6-7 MPa. The purpose of the grinding in the present application is to break the inherent structure of the ore, and after crushing, conditions are created for subsequent separation of lead sulfide. The present application does not have special requirements for the grinding, and the complex lead sulfide ore can be ground into ore powder that is convenient for pressing, and there is no condition that the ore with obvious particles is difficult to separate. The present application prevents the complex lead sulfide ore from escaping and diffusing under vacuum atmosphere by briquetting. The diameter of the briquetting die in the briquetting is preferably 20-40 mm, and the present application does not have special limitations on the briquetting method, and the briquetting method well known to those skilled in the art can be used.

[0032] In the present application, the vacuum degree in the vacuum distillation is 1-10 Pa, preferably 2-6 Pa, and further preferably 3-5 Pa. In the present application, the vacuum degree is controlled to be 1-10 Pa, so that the distillation temperature is lower, and the structure of the solid solution in the original mineral is broken, and the lead sulfide is enriched.

[0033] In the present application, the temperature of the vacuum distillation is 700-1200℃, preferably 750-1100℃, and further preferably 800-900℃; the time is 30-120 min, preferably 50-100 min, and further preferably 60-90 min. The present application preferably carries out the vacuum distillation in a vacuum furnace. In the present application, by controlling the vacuum degree, temperature and holding time of the vacuum distillation, the structure of the solid solution in the original mineral is broken, the lead sulfide is volatilized alone, and the preliminary separation of the crude lead sulfide is realized. In addition, in the process of vacuum distillation, a small amount of antimony sulfide volatilizes together with lead sulfide to form crude lead sulfide, in addition, the crude lead sulfide also includes a small amount of arsenic sulfide and stannous sulfide, which are dissolved in the alkaline solution in the process of alkali leaching.

[0034] In the present application, the temperature of the vacuum distillation is 700-1200℃, preferably 750-1100℃, and further preferably 800-900℃; the time is 30-120 min, preferably 50-100 min, and further preferably 60-90 min. The present application preferably carries out the vacuum distillation in a vacuum furnace. In the present application, by controlling the vacuum degree, temperature and holding time of the vacuum distillation, the structure of the solid solution in the original mineral is broken, the lead sulfide is volatilized alone, and the preliminary separation of the crude lead sulfide is realized. In addition, in the process of vacuum distillation, a small amount of antimony sulfide volatilizes together with lead sulfide to form crude lead sulfide, in addition, the crude lead sulfide also includes a small amount of arsenic sulfide and stannous sulfide, which are dissolved in the alkaline solution in the process of alkali leaching.

[0035] After obtaining the crude lead sulfide, the present application mixes the crude lead sulfide with an alkaline solution for alkali leaching, solid-liquid separation, and obtaining pure lead sulfide.

[0036] In the present application, the alkaline substance in the alkaline solution is preferably NaOH and Na2S, the concentration of Na2S in the alkaline solution is preferably 100-140 g / L, and further preferably 110-135 g / L; the concentration of NaOH is preferably 20-50 g / L, and further preferably 25-45 g / L. In the present application, sodium hydroxide is used as a protective agent for sodium sulfide, and impurities such as antimony sulfide and arsenic sulfide are easily dissolved in sodium sulfide solution, but sodium sulfide is easily hydrolyzed, so sodium hydroxide is added to prevent the hydrolysis of sodium sulfide.

[0037] In the present application, the solid-liquid ratio of the crude lead sulfide to the alkaline solution is preferably 1 g:2-5 mL, and more preferably 1 g:3-4 mL.

[0038] The present application preferably grinds and crushes the crude lead sulfide first, and then mixes it with the alkaline solution.

[0039] In this invention, the crude lead sulfide is preferably further subjected to pulping before being mixed with the alkaline solution for alkaline leaching. The pulping time is preferably 10-20 minutes, more preferably 12-18 minutes. The pulping in this invention is to ensure that the crude lead sulfide and the alkaline solution are fully mixed, so that the subsequent alkaline leaching process reacts fully and no chemical changes occur.

[0040] In this invention, the temperature of the alkali leaching is preferably 60-100°C, more preferably 80-95°C, and the time is preferably 30-120 min, more preferably 60-100 min.

[0041] In this invention, the alkaline leaching is preferably carried out under stirring conditions, and the stirring speed is preferably 500-2000 rpm, more preferably 1000-1500 rpm. This invention does not impose any particular limitation on the stirring; any stirring method well known to those skilled in the art can be used.

[0042] In the alkaline leaching process of this invention, Sb₂S₃ impurities dissolve in the alkaline solution and are separated from PbS after filtration. The reaction equation is as follows:

[0043] Sb₂S₃ + ​​3Na₂S = 2Na₃SbS₃.

[0044] The present invention does not have any particular limitation on the solid-liquid separation, and any solid-liquid separation method known to those skilled in the art can be used, such as centrifugation.

[0045] In this invention, the alkaline leaching is preferably performed once or multiple times. When performing multiple alkaline leachings, it is preferable to mix the solid obtained after solid-liquid separation in the previous alkaline leaching with an alkaline solution and repeat the alkaline leaching step. In this invention, when performing multiple alkaline leachings, the purity of the obtained lead sulfide is higher than that obtained by a single alkaline leaching.

[0046] Figure 1 This is a schematic diagram of the process for preparing lead sulfide according to the present invention, as shown below. Figure 1 As shown, the present invention involves vacuum distilling complex lead sulfide ore to obtain crude lead sulfide; the crude lead sulfide includes lead sulfide and a small amount of antimony sulfide; the crude lead sulfide is mixed with an alkaline solution for alkaline leaching (i.e., wet leaching), and solid-liquid separation is performed to obtain pure lead sulfide and antimony-containing solution; the antimony-containing solution is reduced to obtain elemental antimony.

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to specific examples. The described embodiments are only some embodiments of the present invention, and not all embodiments. Any modifications, equivalent substitutions, improvements, etc., made to the embodiments of the present invention based on the technical essence and general principles of the present invention without creative effort should be within the protection scope of the present invention.

[0048] The elemental composition of the complex lead sulfide ore used in the following examples and comparative examples is as follows: by mass percentage, it includes Pb: 28.93%, Sb: 22.73%, Fe: 12.60%, Zn: 4.89%, S: 25.52%, Ca: 1.07%, Cu: 0.22%, and Sn: 0.3%.

[0049] Example 1

[0050] (1) Grind and briquette a complex lead sulfide ore with a Pb content of 28.93% and an Sb content of 22.73%. The briquetting tool has a diameter of 25 mm and a forming pressure of 5 MPa.

[0051] (2) Place the blocky solid from step (1) into a vacuum furnace, turn on the circulating water, and turn on the vacuum pump to create a vacuum.

[0052] (3) When the vacuum level in step (2) drops to 20 Pa, start heating and adjust the heating rate to 20 °C / min. After the temperature rises to 300 °C, adjust the heating rate to 25 °C / min. When the temperature rises to 800 °C, adjust the heating rate to 28 °C / min. When the temperature rises to 1100 °C, control the pressure inside the furnace at 5 Pa and control the holding time to 60 min before stopping heating.

[0053] (4) After the temperature inside the vacuum furnace cools down to below room temperature, turn off the vacuum pump, collect the product, and obtain crude lead sulfide.

[0054] (5) The obtained crude lead sulfide was re-ground and pulverized, and then mixed with an alkaline solution containing 120 g / L sodium sulfide and 40 g / L sodium hydroxide at a liquid-to-solid ratio of 1 g:5 mL for 15 min. The mixture was then heated to 85 °C and held at 1000 rpm for 60 min. After filtration, the filter residue was dried to obtain lead sulfide. The final lead sulfide obtained had a purity of 90.78% and contained 2.73% Sb.

[0055] Example 2

[0056] The briquetting mold was 30 mm in diameter. Vacuum distillation was performed at 800°C for 90 minutes. The prepared alkaline solution contained 140 g / L sodium sulfide and 50 g / L sodium hydroxide. The alkali leaching was carried out at 1500 rpm, heated to 60°C, and held for 90 minutes. Other steps were the same as in Example 1. The final lead sulfide obtained had a purity of 97.30% and contained 2.72% Sb.

[0057] Example 3

[0058] The briquetting mold is 35 mm in diameter, the temperature of vacuum distillation is 750℃, the time is 120 min, the concentration of sodium sulfide in the prepared alkaline solution is 100 g / L, the concentration of sodium hydroxide is 20 g / L, the rotation speed of alkaline leaching is 2000 rpm, heating to 95℃, and keeping for 30 min. Other steps are the same as those in Example 1. Finally, the purity of lead sulfide is 94.03%, and the content of Sb is 1.54%.

[0059] Example 4

[0060] The final product lead sulfide obtained in Example 1 is ground again, mixed with the prepared alkaline solution with a concentration of sodium sulfide of 120 g / L and a concentration of sodium hydroxide of 40 g / L, and slurried for 15 min, heated to 95℃ under the condition of stirring at 1000 rpm, and kept for 30 min. After filtration, the filter residue is dried to obtain lead sulfide. Other steps are the same as those in Example 1. Finally, the purity of lead sulfide is 95.81%, and the content of Sb is 0.62%.

[0061] Comparative Example 1

[0062] The raw ore of complex lead sulfide ore is ground and crushed, mixed with the prepared alkaline solution with a concentration of sodium sulfide of 100 g / L and a concentration of sodium hydroxide of 20 g / L, and slurried for 15 min, heated to 95℃ under the condition of stirring at 2000 rpm, and kept for 30 min. After filtration, the filter residue is dried to obtain lead sulfide. Finally, the purity of lead sulfide is 37.41%, and the content of Sb is 13.13%.

[0063] The purity of the final lead sulfide obtained in Examples 1-3 is significantly higher than that of the lead sulfide obtained in the comparative example. Example 4 is a secondary alkaline leaching based on Example 1. Because there is still some antimony in the final lead sulfide product after the first alkaline leaching, a secondary alkaline leaching is attempted. The results show that after the secondary alkaline leaching, the separation of antimony is more complete, and the purity is higher.

[0064] The above only describes the preferred embodiments of the present application. It should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing lead sulfide from complex lead sulfide ores, characterized in that, The steps are as follows: (1) A complex lead sulfide ore with a Pb content of 28.93% and an Sb content of 22.73% is ground and briquetted. The briquetting die has a diameter of 25 mm and a forming pressure of 5 MPa. The complex lead sulfide ore includes lead sulfide, antimony sulfide and iron sulfide. The antimony sulfide, iron sulfide and part of the lead sulfide are intercalated together in the form of a solid solution, and the remaining lead sulfide exists independently. (2) Place the blocky solid from step (1) into a vacuum furnace, turn on the circulating water, and turn on the vacuum pump to draw a vacuum. (3) When the vacuum degree in step (2) drops to 20 Pa, start heating and adjust the heating rate to 20℃ / min. After the temperature rises to 300℃, adjust the heating rate to 25℃ / min. When the temperature rises to 800℃, adjust the heating rate to 28℃ / min. When the temperature rises to 1100℃, control the pressure inside the furnace at 5 Pa and control the holding time to 60 min before stopping heating. (4) After the temperature inside the vacuum furnace cools down to below room temperature, turn off the vacuum pump, collect the product, and obtain crude lead sulfide. (5) The obtained crude lead sulfide is re-ground and crushed, and mixed with an alkaline solution with a sodium sulfide concentration of 120 g / L and a sodium hydroxide concentration of 40 g / L at a liquid-solid ratio of 1 g: 5 mL for 15 min. The mixture is then heated to 85 °C at a stirring speed of 1000 rpm and kept at that temperature for 60 min. After filtration, the filter residue is dried to obtain lead sulfide. (6) Grind the lead sulfide obtained in step (5) again, mix it with an alkaline solution with a sodium sulfide concentration of 120 g / L and a sodium hydroxide concentration of 40 g / L and slurry it for 15 min. While stirring at 1000 rpm, heat it to 95°C and keep it warm for 30 min. After filtering, dry the filter residue to obtain lead sulfide. The lead sulfide obtained in step (6) has a purity of 95.81% and contains 0.62% Sb.

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