Method for purifying selenium from selenium-containing material based on alkaline hydrometallurgy technology

Abstract

The invention discloses a method for purifying selenium from a selenium-containing material based on an alkaline hydrometallurgy technology, and belongs to the technical field of small metal metallurgy. The method comprises the following steps: stirring and leaching a selenium-containing material in a NaOH solution at normal temperature, adding hydrazine hydrate, and filtering after the reaction is completed; adding an oxidizing agent H2O2 into the filtrate in a stirring tank, carrying out normal-temperature reduction, and filtering after an oxidation end point to obtain selenium powder with the product grade of more than or equal to 99.5%; and returning the oxidized filtrate to the leaching process for recycling, and supplementing a certain amount of NaOH solid. The method is reasonable in design and high in metal recovery rate, selenium and other associated valuable elements (Au, Ag, Pb, Cu and the like) can be fully recovered, and good economic benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of minor metal metallurgy, and in particular relates to a method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgy technology. Background Art

[0002] Selenium is a rare element with a wide range of applications, but it has always been a severely scarce metal resource. There are few individual mineralizations in nature that are valuable for industrial mining. The main source of selenium is the by-product produced during the smelting of heavy metal sulfide ores, while the selenium production from copper electrolysis anode mud and copper sulfide ore smelting dust accounts for about 90% of the total selenium production. The rest is recovered from various dust, blue powder and anode mud produced by lead, cobalt and nickel refining, as well as acid mud produced by sulfuric acid production and washing mud produced by pulping.

[0003] At present, the main methods for recovering selenium from anode mud at home and abroad are chemical and physical methods. There are two types of methods, namely, sulfuric acid roasting-reduction method, sulfuric acid roasting-distillation method, sulfuric acid roasting-alkaline leaching method, segmented sulfuric acid roasting method and dry sulfuric acid roasting method, solvent extraction method, vacuum distillation method, ion exchange method, soda ash roasting method, etc., which can separate selenium from other impurities. Although the physical method for purifying selenium has significant advantages such as short process, high purification efficiency and high direct yield, it has high requirements on the selenium content of the raw materials and high requirements on equipment. Among them, the widely used vacuum distillation method has poor removal effect on the impurity metal tellurium, thus affecting the purity of the product. Among them, the sulfuric acid roasting-reduction method has simple process and large processing capacity, but there is a serious sulfur dioxide flue gas problem. Traditional chemical purification requires multiple phase transformations of selenium, which is costly and has strong applicability to raw materials, but has the disadvantages of long process, complex operation, and large amount of three wastes. Summary of the invention

[0004] In view of the shortcomings of the above-mentioned prior art, the present invention provides a method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology. The selenium-containing material is catalytically leached in a NaOH solution at room temperature under the catalysis of hydrazine hydrate, and then high-grade selenium is purified by a process technology of oxidative purification at room temperature using hydrogen peroxide, with the purpose of providing a new and reasonable process design; the method for purifying selenium is an original new method, which is a combination of selective leaching and reduction processes, has a simple process, is pollution-free in the production process, and has low production costs.

[0005] A method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology, the specific steps are as follows:

[0006] (1) Alkaline leaching of selenium-containing materials: Initially, 80-85% of the volume of tap water is added to the stirred reaction tank;

[0007] Calculate the mass of solid sodium hydroxide added based on the NaOH concentration of the starting solution being 150-210 g / L;

[0008] Calculate the mass of the added selenium-containing material according to the solid-liquid ratio of solid:liquid = 1:4-10;

[0009] Slowly add a measured amount of hydrazine hydrate catalyst: the mass of hydrazine hydrate added is 2-6% of the mass of the selenium-containing material; after adding the catalyst, stir and react for 2-3 hours at normal temperature and pressure, the reaction is fast, a certain amount of heat is released, and the liquid temperature rises to 50-80°C; when the reaction time is up, filter to achieve solid-liquid separation, and the filter residue is concentrated and stored at a fixed location, and the leaching liquid is dark red, opaque but clear; the NaOH concentration of the leaching liquid is controlled at: 80-140g / L; the selenium content in the selenium-containing material is: 5%-95%.

[0010] (2) Oxidation of selenium: initially, 65% to 75% of the leaching solution by volume is added to the stirred reaction tank. During reduction, the NaOH concentration of the solution is required to be controlled at 80 to 140 g / L. Then, an oxidant, hydrogen peroxide (H2O2), is added according to the stoichiometric amount of the oxidation reaction. H2O2 should be added slowly, and the reaction is fast, releasing a large amount of heat, and the liquid temperature rises to 70 to 95°C. When the color of the solution disappears from deep red and turns into light yellow, clear and transparent, it indicates that the reduction end point has been reached. Stop adding H2O2, continue stirring the reaction for 15 to 25 minutes, and then filter with a centrifuge to achieve solid-liquid separation. The filtrate is returned to the leaching process for recycling. The selenium powder obtained by filtration is washed 2 to 4 times with pure water at room temperature. The pH of the washing water is 6.5 to 7.5, which is the washing end point. The Se grade of the obtained pure selenium powder is ≥99.5%.

[0011] The selenium-containing material described in the present invention comprises elemental selenium and selenide; the selenide is one or more of H2Se, ammonium selenide, aluminum selenide, zinc selenide, arsenic selenide, antimony selenide, mercury selenide, sodium selenide, iron selenide, alkali metal selenides, and alkaline earth metal selenides.

[0012] More preferably, the selenium-containing material comprises one or more of the following components: elemental selenium, H2Se, ammonium selenide, aluminum selenide, zinc selenide, arsenic selenide, mercury selenide, antimony selenide, sodium selenide, and iron selenide.

[0013] The NaOH concentration of the starting solution of the present invention is controlled at 150-210 g / L; if the NaOH concentration is less than 150 g / L, the Se leaching rate is low; if the NaOH concentration is greater than 210 g / L, the Se leaching rate is very high, and at the same time, it brings great harm to the next step of Se reduction.

[0014] The selenium leaching rate of the selenium-containing material of the present invention is 95-99.5%.

[0015] The Se content in the leaching solution of the present invention is 20-120 g / L; the optimal Se concentration of the leaching solution is 55-70 g / L; when the Se concentration of the leaching solution is less than 50 g / L, the production economy is poor; when the Se concentration is ≥75 g / L, a certain amount of selenium is naturally reduced when the liquid surface contacts the air, and the higher the selenium concentration, the faster the natural reduction speed, which affects the selenium leaching rate and the grade of the selenium product when reducing selenium.

[0016] The active ingredient content of the hydrazine hydrate catalyst of the present invention is 80%. In the alkaline leaching process of selenium materials, hydrazine hydrate plays two roles: 1. Elemental selenium and selenide play a catalytic role during alkaline leaching, accelerating the conversion of elemental selenium and selenide into sodium selenide, thereby improving the leaching rate of selenium. 2. Rapidly reducing a very small amount of sodium selenite in the alkaline solution into sodium selenide, thereby improving the direct reduction yield of selenium.

[0017] The filtration process of solid-liquid separation of the leachate described in the present invention: in order to ensure the acquisition of high-purity selenium products, the leachate is required to be filtered twice, the first time is a coarse filtration, mainly filtering most of the leaching residues; the second time is a precise filtration, which is to filter the filtrate once, mainly filtering fine suspended particles.

[0018] The reduction of selenium in the present invention requires that the NaOH concentration in the leaching solution be controlled at 80-140 g / L; within this concentration range, Se is easily reduced and precipitated. If the NaOH content is greater than 140 g / L, the reduced elemental selenium powder will dissolve back in a short time, and the reduction is incomplete; if the NaOH content is greater than 170 g / L, 50-80% of the reduced elemental selenium powder will dissolve back within 10-20 minutes.

[0019] The present invention tests the Se content in the leachate and the added N2H4 content by conventional testing methods in the art, adds the oxidant H2O2 according to the stoichiometric amount of the reduction reaction, and the oxidation reaction is the oxidation reaction of hydrazine hydrate and H2O2 and the oxidation reaction of sodium selenide in the leachate and hydrazine hydrate.

[0020] More preferably, the amount of H2O2 added can be excessive, but the amount of hydrogen peroxide should be controlled not to exceed 10%. The effective component of the hydrogen peroxide oxidant of the present invention is 50% or 30%.

[0021] In the selenium oxidation process of the present invention, the direct reduction yield of selenium is 90-96%.

[0022] The oxidized filtrate of the present invention contains 0.7-6 g / L of Se, and the oxidized filtrate is returned to the leaching process for recycling.

[0023] Selenium-containing materials on the market are divided into three categories based on their properties and corresponding processing technologies:

[0024] The first category of selenium-containing materials mainly contain selenium-containing substances such as selenium dioxide, selenium sulfite, selenium chloride, ammonium selenite, sodium thioselenate, sodium selenite, copper selenite and other selenites, as well as sodium selenate, lead selenate and other selenates, which need to be directly leached by chlorination method and reduced to selenium products in one step.

[0025] The second category of selenium-containing materials mainly contain selenium-containing substances such as elemental selenium, H2Se, ammonium selenide, aluminum selenide, zinc selenide, arsenic selenide, mercury selenide, antimony selenide, sodium selenide, iron selenide, etc. and selenides of alkali metals and alkaline earth metals, which are directly leached by the method of purifying selenium from selenium-containing materials using alkaline hydrometallurgical technology as described in the present invention, and reduced to selenium products in one step.

[0026] The third category of selenium-containing materials mainly contain selenium-containing substances such as copper selenide, silver selenide, mercury selenide, nickel selenide, lead selenide and other heavy metal selenides, precious metal selenides, and rare metal selenides. It is necessary to first use chlorination method to obtain selenium-enriched slag, and then use the method of purifying selenium from selenium-containing materials using alkaline hydrometallurgy technology as described in the present invention to obtain selenium products, or first use the method of purifying selenium from selenium-containing materials using alkaline hydrometallurgy technology as described in the present invention to obtain leaching slag, and then use chlorination method to treat it. The grade and recovery rate of the selenium product finally obtained are higher.

[0027] The alkaline leaching principle of the selenium-containing material involved in step (1) of the present invention is as follows: According to the characteristics of the selenium-containing material, in the NaOH solution system, under the action of the catalyst hydrazine hydrate, the selenium-containing material is leached at room temperature, and selenium is selectively leached, with a leaching rate of 95-99.5%. The main chemical reaction formula is as follows:

[0028] Hydrazine hydrate

[0029] Main reaction: 3Se+6NaOH=2Na2Se+Na2SeO3+3H2O

[0030] Al2Se3+6NaOH=3Na2Se+2Al(OH)3↓

[0031] ZnSe+2NaOH=Na2Se+Zn(OH)2↓

[0032] H2Se+2NaOH=Na2Se+2H2O

[0033] As2Se3+12NaOH=3Na2Se+2Na2AsO3+6H2O

[0034] Second reaction: 2Na2SeO3+3N2H4=2Na2Se+3N2↑+6H2O

[0035] The oxidation principle of selenium involved in step (2) of the present invention is as follows: 2- The present invention selects hydrogen peroxide as an efficient and highly selective oxidant. By controlling the alkalinity, selenium can be completely oxidized, and a large amount of heat is released during oxidation. The main chemical reaction formula is as follows:

[0036] Na2Se+H2O2=Se↓+2NaOH

[0037] N2H4+2H2O2=N2↑+4H2O

[0038] The oxidized selenium powder should be washed with pure water until it reaches neutral pH 7.0.

[0039] Compared with the existing selenium smelting and purification technology, the present invention has the following advantages:

[0040] (1) The production cost is low and the product pure selenium powder grade is ≥99.5%.

[0041] (2) The leaching process in the method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology described in the present invention is a selective leaching process, which only leaches selenium, and other metals such as tellurium are basically not leached. Therefore, the production solution does not need to be purified during the circulation production process, there is no environmental pressure, the environmental protection management is simple, there is no secondary pollution, and it is a clean production process; the process energy consumption is very low.

[0042] (3) The process flow is simple, the production equipment is simple, the construction investment is small, and the construction period is short.

[0043] (4) The production process is flexible and can realize building block-style process changes, which is a flexible production line.

[0044] (5) The recovery rate of valuable elements is as high as ≥98%.

[0045] (6) Using the process technology of the present invention, if each process is precisely controlled, high-purity selenium products can be produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The present invention is a flow chart of the method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgy technology. DETAILED DESCRIPTION

[0047] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0048] A method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology comprises the following steps:

[0049] (1) Alkaline leaching of selenium-containing materials: At the beginning, tap water of 80-85% of the volume of the tank is added to the stirred reaction tank (any value within the range can be taken, such as 80%, 81%, 84%, 85%...); the mass of solid sodium hydroxide added is calculated according to the NaOH concentration in the starting solution of 150-210 g / L (any value within the range can be taken, such as (150 g / L, 180 g / L, 200 g / L, 210 g / L...); the solid-liquid ratio is solid: liquid = 1:4-10 (any value within the range can be taken); The mass of the selenium-containing material is calculated by the ratio of the mass of the selenium-containing material to the catalyst: hydrazine hydrate; the mass of the hydrazine hydrate added is 2-6% of the mass of the selenium-containing material (it can be any value within the range, such as 2%, 3%, 4%, 5%...); after adding the catalyst, the reaction is stirred at room temperature and pressure for 2-3 hours, and the liquid temperature is raised to 50-80°C; when the reaction time is up, filtering is carried out to achieve solid-liquid separation, and the filtered residue is centrally stored at a fixed location, and the filtrate is the leachate.

[0050] (2) Oxidation of selenium: Initially, add 65% to 75% (any value within the range, such as 65%, 67%, 70%, 75% ...) of the leachate by volume to the stirred reaction tank, and the NaOH concentration is 80 to 140 g / L (any value within the range, such as 80 g / L, 90 g / L, 140 g / L ...). Then, add the oxidant H2O2 according to the stoichiometric amount of the reduction reaction, and raise the liquid temperature to 70 to 95°C. When the color of the solution disappears from deep red, When the solution loses its original value and turns light yellow, clear and transparent, it indicates that the reduction end point has been reached. Stop adding H2O2 water, and continue to react with stirring for 15 to 25 minutes (it can take any value within the range, such as 15, 16, 17, 25 minutes...), then filter it with a centrifuge to achieve solid-liquid separation, and return the filtrate to the leaching process for recycling. The selenium powder obtained by filtration is washed with pure water at room temperature for 2 to 4 times, and the final washing water pH is 6.5-7.5, which is the washing end point. The obtained product is pure selenium powder with a Se grade of ≥99.5%.

[0051] Example 1

[0052] A method for purifying selenium from high-content selenomercuric acid mud based on alkaline hydrometallurgy technology comprises the following steps:

[0053] The main components of high-content selenomercuric acid mud include the following elements in percentage by mass: Se: 66.23%, Hg: 32.5%, Te: 0.26%, Pb: 0.5%, Fe: 0.15%.

[0054] The electronic phase analysis results of high-content selenomercuric acid mud are shown in the following table:

[0055]

[0056]

[0057] From the phase analysis, it can be seen that elemental selenium accounts for 80.69% of the total selenium.

[0058] The acid mud only uses a method based on alkaline hydrometallurgy technology to purify selenium from high-content mercury-selenium acid mud to leach and purify elemental selenium, and the selenized mercury is left in the slag to be treated.

[0059] (1) Leaching:

[0060] Fixed conditions: particle size of high-content selenomercuric acid sludge: about 200 mesh, medium stirring intensity, room temperature, amount of N2H4 catalyst added: 3% of the mass of high-content selenomercuric acid sludge, initial concentration of NaOH: 180g / L.

[0061] The relationship between selenium leaching rate, solid-liquid ratio and leaching time was examined.

[0062] Test results:

[0063] 1) Relationship between selenium leaching rate and solid-liquid ratio

[0064] Leaching time: 2h. The results of selenium leaching rate and solid-liquid ratio are shown in the following table:

[0065] Solid-liquid ratio 1︰4 1︰5 1︰6 1︰8 Selenium in the leaching solution 75~97g / L 68~74g / L 55~68g / L 50~55g / L Selenium leaching rate 73.6％ 78.3％ 79.5％ 80.3％ Elemental selenium leaching rate 91.215％ 97.04％ 98.53％ 99.52％

[0066] It can be seen from the experiment that the leaching solution is dark blood red and opaque. The higher the selenium concentration (>75g / L), the more selenium is naturally reduced when it comes into contact with air. It can be seen from the table that when the solid-liquid ratio is 1:5, the leaching rate of elemental selenium reaches 97.04%, which meets the technical requirements; when the solid-liquid ratio is 1:8, the leaching rate of elemental selenium reaches 99.52%. The selenium content of the leaching solution should be controlled between 55g / L and 70g / L, not too high. It can be seen that the leaching rate of elemental selenium is consistent with the results of phase analysis.

[0067] 2) Relationship between selenium leaching rate and leaching time

[0068] When the solid-liquid ratio is 1:5, the results of selenium leaching rate and leaching time are shown in the following table:

[0069] Leaching time 2h 3h Selenium leaching rate 78.3％ 79.7％

[0070] It can be seen from the experiment that a leaching time of 2 hours can meet the technical requirements. Of course, the longer the leaching time, the better, and the higher the leaching rate.

[0071] (2) Selenium oxidation test

[0072] The oxidation of selenium is relatively simple. When the oxidant H2O2 is slowly added to the deep blood-red extract, elemental selenium is oxidized. The reduction ends when the blood-red color disappears and the liquid turns into a transparent light yellow color.

[0073] The results of each 500ml comprehensive liquid oxidation test are shown in the following table:

[0074] name Liquid containing selenium <![CDATA[Amount of H2O2]]> Restore time Selenium in residual liquid Refined selenium grade Selenium reduction rate content 61.48g / L 40ml 1.5h 5.8g / L 99.7％ 90％

[0075] From the experiment, it can be seen that selenium can only be oxidized when the NaOH content in the leaching solution is less than 140g / l. If the oxidation is carried out under high alkali concentration conditions, the oxidized elemental selenium will dissolve back in a short time. When the oxidation residue returns to the leaching, alkali needs to be supplemented, but it does not affect the leaching rate of selenium. The effective ingredient content of the reducing agent H2O2 is 30%, and the unit consumption of hydrogen peroxide is: 1.45t / t Se .

[0076] (3) The final test results are shown in the following table:

[0077] name Se leaching rate Slag rate Selenium content in slag Primary oxidation rate Refined selenium grade content 77～79％ 37～40％ 28～30％ 89～91％ ≥99.5％

[0078] Example 2

[0079] Formal production and processing of selenium slag: This selenium slag is obtained by extracting mercury from 39 tons of selenium-containing mercuric acid mud by chlorination, i.e., leaching slag. The selenium slag contains HgSe, elemental Se, etc. Selenium is purified by the method for purifying selenium from high-content selenium-containing mercuric acid mud based on alkaline hydrometallurgy technology described in the present invention, that is, mercury is first extracted by chlorination method, and then selenium is extracted by the method for purifying selenium from high-content selenium-containing mercuric acid mud based on alkaline hydrometallurgy technology.

[0080] (1) Raw materials: Composition analysis of selenium-containing mercuric acid mud.

[0081] The wet weight of a batch of selenium-mercuric acid sludge purchased for this production is 39.0 tons, and the moisture content is 24.61%. The comprehensive sample was taken for analysis, and the chemical composition and phase analysis results are as follows:

[0082] The comprehensive composition of selenium-containing mercuric acid mud is: Se: 23.24%, Hg: 30.9%, Te: 0.05%, Pb: 5.03%, Fe: 17.74%, Cu: 0.1%, Zn: 1.55%, As: <0.1%.

[0083] Rock composition: SiO2: 5.97%, Fe2O3: 25.33%, CaO: 1.23%, MgO: 0.38%, Al2O3: <0.05%.

[0084] Results of electronic phase analysis of selenomercuric acid mud:

[0085] phase of matter HkDJ Se <![CDATA[Fe2O3]]> <![CDATA[CaSO4·2H2O]]> <![CDATA[PbSO4]]> <![CDATA[SiO2]]> other content(%) 43.06 11.08 25.33 3.78 7.36 5.97 3.42

[0086] From the phase analysis, it can be seen that elemental selenium accounts for 47.68% of the total selenium.

[0087] (2) Selenium slag produced by chlorination process

[0088] Chlorination method: weigh a certain amount of selenium-containing mercuric acid mud material each time, add it to the stirring tank according to a certain amount of solid: liquid = 1: 3-4 (solid-liquid ratio in this embodiment is 1: 3), control the initial HCl concentration to 170-200g / l (HCl concentration in this embodiment is 200g / l), add sodium chlorate by mass to 5%-8% of the material amount (in this embodiment, the sodium chlorate added by mass is 8% of the material amount), and leaching for 2 hours at room temperature; after leaching is completed, filter it with a box filter to achieve solid-liquid separation, and the filtrate enters the leachate storage tank, and the filter residue is concentrated and stored at a fixed location. The leachate is returned to the leaching cycle, and the leachate is qualified when the mercury content is close to the saturation concentration (mercury 200g / l). The qualified leached liquid is pumped to the selenium reduction tank, and the liquid is stopped after a certain amount of liquid is reached. A certain amount of sodium sulfite reducing agent is added to the reduction tank for reduction, and the reduction is stirred for 3 hours to reduce to the end point. The qualified deselenium liquid is filtered by a box filter to achieve solid-liquid separation, and the filtrate enters the deselenium liquid storage tank, and the selenium slag is stored in a fixed location. The qualified deselenium liquid is pumped to the neutralization tank, and the liquid is stopped after a certain amount of liquid is reached. A certain amount of sodium hydroxide is added to the neutralization tank for neutralization, and the end point pH value is controlled at 8-9. The neutralization qualified liquid is filtered by a box filter to achieve solid-liquid separation, and the filtrate enters the neutralization liquid storage tank. The neutralization slag is stored in a fixed location and returned to the leaching process. The qualified neutralization liquid is pumped to the mercury precipitation tank, and the liquid is stopped after a certain amount of liquid is reached. A certain amount of hydrazine hydrate reducing agent is added to the mercury precipitation tank for reduction precipitation. When there is no white mercurous chloride precipitation, the end point is reached. After the mercury precipitation is completed, it is filtered by a centrifuge to achieve solid-liquid separation, and the filtrate enters the liquid storage tank after mercury precipitation. The solid product (pure mercurous chloride) is sampled and then packed in iron barrels and stored in the warehouse. The liquid after mercury precipitation is pumped into the leaching tank for the next cycle of leaching and reduction production process, realizing the closed-loop circulation of the production solution. Part of the liquid after mercury precipitation is periodically treated in an open circuit.

[0089] The chlorination wastewater is finally deeply purified and concentrated to obtain industrial salt. The selenium slag produced has a slag rate of 49.5% and a slag dry weight of 14.554t. The main components of the selenium slag are as follows:

[0090] Main average components of leaching residue (selenium residue):

[0091] name Se Hg <![CDATA[Fe2O3]]> <![CDATA[PbSO4]]> <![CDATA[SiO2]]> other content(%) 40.52 ＜0.014 27.72 14.87 12.06 4.846

[0092] The composition changes of the leached residue are related to the composition of the selenium-containing mercuric acid mud, especially to mercury, selenium, lead and iron.

[0093] (3) The method for purifying selenium from high-content mercuric selenium acid mud based on alkaline hydrometallurgy technology of the present invention is used to treat the selenium slag

[0094] ①Main production equipment:

[0095] name Mixing tank Chamber filter press Middle pool Production liquid pool Slurry pump Centrifuge quantity 3 sets 1 set 1 6 1 unit, 7.5kw 1 unit, 11kw Specification Φ1.2×1.2m <![CDATA[15m 2 ]]> 2×1.5×1.5m 2×2×1.5m <![CDATA[H:40m,Q:12m 3 / h]]> Φ1000

[0096] The mixing tank is made of δ6 thick 1Cr18Ni9Ti stainless steel plate; the liquid pool is built with red bricks and made of glass fiber reinforced plastic for corrosion protection. The pump is a plastic self-priming pump with a head of 10 meters and a flow rate of 5 to 6m 3 / h, motor power: 0.5~1kw, about 8 units. Slurry pump model: 50UHB-2K-B-12-40.

[0097] Three sets of stainless steel stirring tanks: two sets as leaching stirring tanks and one set as reduction tank.

[0098] ②Production technical conditions:

[0099] a. Leaching of Se in leaching residue: solid: liquid = 1:4, liquid inlet per tank: 1.0m 3 , add selenium-containing leaching residue: 250kg, stir and leach at room temperature;

[0100] b. Initial NaOH concentration: 200 g / L, final alkali: 100-120 g / L;

[0101] c. Hydrazine hydrate catalyst: the mass is 3% of the leached slag, i.e., add 7.5 kg per tank;

[0102] d. Leaching time: 5h, i.e., 1h for feeding, 3h for reaction, and 1h for discharging;

[0103] e. Selenium content in leaching solution: about 92g / L;

[0104] f. Oxidation of selenium in solution: 1.0m3 of leaching solution is added to each tank. 3 , oxidized at room temperature.

[0105] g. Add H2O2 oxidant dosage: 93kg per tank (content 50%). End point judgment: the solution changes from blood red to light yellow, clear and transparent, which is the end point.

[0106] ③Technical control indicators

[0107] a. Selenium leaching rate: ≥96.0%;

[0108] b. Primary oxidation rate: ≥90.0%;

[0109] c. Final direct yield of selenium: ≥95%;

[0110] d. Selenium grade: ≥99.5%;

[0111] ④Production results

[0112] a. Dissolution of selenium-containing slag during leaching:

[0113] name Dissolution rate Primary slag rate content 43.5％ 56.5％

[0114] Note: The dissolution rate is only related to the selenium content in the chlorination leaching residue.

[0115] b. Selenium content of the product:

[0116] name Se other content(%) 99.7 ＜0.3

[0117] c. The main components of the leaching residue obtained by purifying selenium from high-content selenium-mercuric acid mud based on alkaline hydrometallurgical technology are:

[0118] name Se <![CDATA[Fe2O3]]> <![CDATA[PbSO4]]> <![CDATA[SiO2]]> other content(%) 1.84 49.06 26.32 17.73 5.05

[0119] d. Technical indicators

[0120] name Selenium leaching rate Slag rate Selenium primary oxidation rate Final direct yield of selenium Selenium Grade Numeric 97.43％ 56.5％ 91.5％ 96.0％ 99.7％

[0121] (4) Production results statistics

[0122] After one and a half months of production, 39 tons of acid sludge have been processed. The production data results are as follows:

[0123] Production data statistics of acid sludge after treatment

[0124] Income and output of various materials table:

[0125]

[0126]

[0127] ②Technical and economic indicators

[0128] Technical and economic indicators of processed materials:

[0129] (1) Selenium leaching rate: 97.43%, selenium direct recovery rate: 96.0% (average value);

[0130] (2) Mercury leaching rate: 99.98%, mercury direct recovery rate: 99.90% (average value);

[0131] (3) Primary leaching residue rate: 27.97% (ratio of leaching residue to feed amount.)

[0132] (4) Primary neutralization slag rate: 21.36% (the ratio of the amount of neutralized slag produced in one time to the amount of feed)

[0133] (5) Final residue rate: 36.52% (the ratio of the final residue amount to the feed amount.)

[0134] (6) Comprehensive power consumption: 3500KW·h / tSe;

[0135] (7) Comprehensive water consumption: 10 meters 3 / tSe;

[0136] (8) Hydrochloric acid unit consumption: 13.5t / tSe;

[0137] (9) Sodium chlorate unit consumption: 0.35t / tSe;

[0138] (10) Sodium sulfite consumption: 1.1t / tSe;

[0139] (11) Hydrazine hydrate unit consumption: 0.4t / tSe (mostly used for mercury reduction);

[0140] (12) Sodium hydroxide unit consumption: 3.0t / tSe;

[0141] (13) Hydrogen peroxide unit consumption: 1.1t / tSe (content 50%), 1.8t / tSe (content 30%);

[0142] (14) Sodium sulfide unit consumption: 0.1t / tSe;

[0143] (15) Direct processing cost of selenium product: RMB 82,000 / tSe (all costs are amortized to selenium products, and mercury is zero amortized; direct processing costs do not include depreciation of fixed assets and raw material costs.).

[0144] ③Metal balance results

[0145] This metal balance is based on the purchased 39.0t acid sludge, and the metal balance of the whole process is carried out after the production is completed.

[0146] ·Selenium metal balance table after acid mud production:

[0147]

[0148]

[0149] The error rate is 1.3%, which is within 5%, indicating that the data is reliable; the error is mainly caused by errors in sampling the purchased raw materials and analysis errors.

[0150] Mercury metal balance after acid sludge production:

[0151]

[0152] The error rate is 1.7%, which is within 5%, indicating that the data is reliable; the error is mainly caused by the error in the bulk sampling of the purchased raw materials and the analysis error. According to the quantitative analysis statistics of the unit production, the direct recovery rate of mercury is 99.9%.

[0153] ④Consumption and cost of raw materials and auxiliary materials

[0154] The number and cost of various materials consumed in the entire production are shown in the following table:

[0155] name Auxiliary material consumption Consumption costs Buy acid mud 39.0t 260464.0 yuan hydrochloric acid 104.0t 57276.0 yuan Sodium chlorate 2.4t 12178.0 yuan Sodium sulfite 10.0t 30000.0 Yuan Hydrazine hydrate 3.41t 91247.8 yuan Sodium hydroxide 21.0t 91350.0 Yuan Hydrogen Peroxide 15.8t 29388.0 yuan Sodium sulfide 1.0t 2600.0 Yuan other 3.0t 9000.0 Yuan water <![CDATA[12422.0m 3 ]]> 27234.9 yuan electricity 125607.0 degrees 83071.5 yuan total 693810.2 yuan

[0156] ⑤Construction cost of this production line

[0157] Alkali process production line of the present invention: RMB 150,000

[0158] Chlorination production line: RMB 200,000

[0159] Other construction: 150,000 yuan

[0160] Total: RMB 500,000.

[0161] ⑥Product sales revenue

[0162] Total revenue from sales of selenium products: RMB 3.7126 million

[0163] Total revenue from mercury product sales: RMB 1,568,400

[0164] Other total income: RMB 0.0 million

[0165] Total: 5.281 million yuan.

[0166] Example 3

[0167] The method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology of the present invention can process a mixture of elemental sulfur and elemental selenium that is special in the market. The processing process is described as follows:

[0168] ⑴ Composition of the mixture of elemental sulfur and elemental selenium

[0169] Se: 16 to 20%, S: 60 to 75%.

[0170] ⑵Processing steps

[0171] A: Leaching

[0172] Sodium hydroxide concentration: 160-180g / L; leaching temperature: 40-70℃; solid: liquid = 1:4-5; add hydrazine hydrate amount according to calculation, stir and react for about 4 hours; filter when the time is up, the leaching liquid is blood red.

[0173] B: Oxidation

[0174] Use hydrogen peroxide to oxidize, add hydrogen peroxide slowly, oxidize red selenium, and an explosion will occur on the surface of the liquid. For production safety, hydrogen peroxide must be added slowly.

[0175] When no red selenium is produced on the surface of the liquid, it reaches the end point and stop adding hydrogen peroxide. When adding hydrogen peroxide, the liquid temperature will slowly rise to above 50 degrees. Stir the reaction for about 3 hours and the red selenium will turn into black selenium. Then 99% of the refined selenium can be filtered out.

[0176] Note: Do not add excessive amount of hydrogen peroxide, otherwise the selenium will be oxidized and no product will be obtained; when the end point is reached, the explosion phenomenon will also disappear.

[0177] C: Treatment of residual liquid

[0178] After the oxidation solution is returned to the leaching process and leached for about 3 cycles, it needs to be treated due to excessive sulfur content. The treatment method is to use hydrochloric acid to neutralize and precipitate sulfur and a small amount of selenium in steps:

[0179] Step 1: Neutralize with hydrochloric acid until the pH value reaches 5-7. A large amount of sulfur will precipitate. Filter to separate the sulfur and liquid.

[0180] Step 2: The filtered liquid is further adjusted to a pH of 1 to 1.5 with hydrochloric acid and stirred for 2 hours. At this time, selenium and part of sulfur are oxidized and separated by filtration. The end point is when the liquid is tested for selenium-free.

[0181] Note: Before adding hydrochloric acid to the residual liquid, it must be treated with hydrogen peroxide until the explosion disappears; if the oxidized liquid is neutralized with hydrochloric acid without being treated with hydrogen peroxide, hydrogen sulfide gas will be produced, which is unsafe for personnel.

[0182] D: Technical indicators

[0183] Selenium leaching rate: ≥99%;

[0184] Selenium powder direct recovery rate: about 96%, final recovery rate: 98.0%;

[0185] Sulfur powder recovery rate: about 97%.

[0186] Example 4

[0187] Treatment of a high-selenium-containing miscellaneous material:

[0188] The selenium-containing material was purchased by the company from the market, with a total weight of 2378.3 kg. The main components are: Se: 66.12%, Te: 0.32%, others: 33.56%, and H2O: 28.90%.

[0189] The present invention firstly adopts a method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgy technology to purify most of the selenium, and then uses a chlorination method to purify the last small part of the selenium, and achieves the expected effect after 25 days of production.

[0190] (1) Leaching process: ① Conditions: solid: liquid = 1: 6, leaching time: 3 hours; leaching under stirring at room temperature; initial NaOH concentration: 200 g / L, final alkali: 100-120 g / L; hydrazine hydrate catalyst: mass is 3% of the leaching residue.

[0191] ②Production indicators: Leaching rate: 84.5%, NaOH consumption: 1.12t / t Se , slag rate: 40.15%, slag selenium content: 26.86%.

[0192] (2) Oxidation process: ① Conditions: Oxidation time: 2.0 hours.

[0193] ②Production indicators: Se reduction rate: 97.6%, hydrogen peroxide consumption: 2.1t / t Se (Hydrogen peroxide content: 30%), residual liquid contains Se: 0.73g / L.

[0194] ③ At the end of oxidation, the amount of hydrogen peroxide should be controlled so that it cannot be too much, and can only be about 8% in excess.

[0195] Oxidation products: The grade of selenium powder after primary oxidation is 97% to 98%, and the grade of selenium powder after washing is ≥99.5%.

[0196] (3) The leaching residue obtained by purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology was treated by the chlorination method described in Example 2. The treatment results were as follows: the final selenium direct recovery rate could reach 90%, the residue rate was 5-8%, and the selenium content of the residue was about 2%.

[0197] Production results: Wet weight of refined selenium: 1243.38 kg (without washing);

[0198] Average moisture: 15.653%;

[0199] Grade (dry): 97.5%;

[0200] Selenium metal content: 1022.53kg;

[0201] The output by-product mercurous chloride has a wet weight of 143.35 kg, mercury grade of 78.21%, and moisture of 10.11%.

[0202] Table 1: Metal balance of selenium

[0203]

[0204] Table 2: Direct production costs of refined selenium

[0205] name consumption unit price Consumption cost (yuan) hydrochloric acid 1506.0kg 620 yuan / ton 933.72 <![CDATA[NaClO4]]> 12.5kg 2600 yuan / ton 32.50 <![CDATA[H2O2]]> 2150.0kg 3130 yuan / ton 6729.50 Hydrazine hydrate 285kg 36.30 Yuan / kg 10345.50 NaOH 1113.0kg 3100 yuan / ton 3450.30 Dose 3 0.45kg 35.30 Yuan / kg 15.88 electricity 1230.0 degrees 0.68 yuan / kWh 836.40 water <![CDATA[94.0m 3 ]]> <![CDATA[3.5 yuan / m 3 > 329.0 total 22672.80

[0206] Example 5

[0207] Treatment of a high-grade selenium-containing material:

[0208] The selenium-containing material was purchased by the company from the market, with a total weight of 481.0 kg and main components: Se: 71.30%, Hg: 13.86%, others: 14.84%, H2O: 18.66%.

[0209] The present invention adopts a method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgy technology to purify most of the selenium, and then uses a chlorination method to purify the last small amount of selenium and recover mercury; through analysis of production data, the treatment method of this embodiment also achieves very good results for treating high-grade selenium-containing materials, and the results are:

[0210] ① Feeding amount: 481.0kg, Se: 71.3%, Hg: 13.86%, H2O: 18.66%, and a certain amount of elemental mercury. The dry weight of the material: 391.25kg, selenium metal content: 278.96kg, mercury metal content: 54.23kg.

[0211] ②Product output: 302kg, containing Se: 92.48%, H2O: 18.37%. The dry weight of the product: 246.5226kg, selenium metal content: 227.98kg. (The leaching solution was only coarsely filtered once, and the selenium grade of the product was low; the product was not washed.)

[0212] ③ Leaching residue: total weight 79.6kg, containing Se: 19.11%, H2O: 16.48%, Hg: 30.76% (lower in internal analysis). The dry weight of the residue is 66.482kg, and the amount of selenium metal is 12.70kg.

[0213] ④Final residual liquid: Pool 1: 1.6m 3 , Se: 9.96g / L; Pool 2: 2.84m 3 , Se: 7.52g / L. Then the residual liquid contains selenium metal: 1.6×9.96+2.84×7.52=37.29kg. (The residual liquid is not treated to recover selenium)

[0214] ⑤ Auxiliary material consumption:

[0215] H2O2: 238.9kg;

[0216] HCl: 40.0 kg;

[0217] Hydrazine: 50.5 kg;

[0218] Alkali: 895.0kg.

[0219] ⑥ Selenium metal balance

[0220]

[0221] ⑦ Auxiliary material consumption

[0222] name Auxiliary material consumption <![CDATA[H2O2]]> <![CDATA[1.048t / t Se ]]> HCl <![CDATA[0.175t / t Se ]]> Hydrazine hydrate <![CDATA[0.19t / t Se <!-- 12 -->]]> NaOH <![CDATA[3.926t / t Se ]]>

Claims

1. A method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology, characterized in that: The steps include: (1) Alkaline leaching of selenium-containing materials: Initially, add 80-85% of the tank volume of tap water into the stirred reaction tank; Calculate the mass of solid sodium hydroxide added to tap water based on the NaOH concentration in the starting solution being 150-210 g / L; Calculate the mass of the added selenium-containing material according to the solid-liquid ratio of solid:liquid = 1:4-10; Slowly add hydrazine hydrate catalyst in an amount of 2-6% of the mass of the selenium-containing material; after adding the catalyst, stir and react for 2-3 hours at room temperature and pressure, and raise the liquid temperature to 50-80° C.; when the reaction time is up, filter to achieve solid-liquid separation; wherein the filter residue is centrally stored, and the NaOH concentration of the leaching solution is controlled at: 80-140 g / L; (2) Oxidation of selenium: Add H2O2 oxidant according to the stoichiometric amount of the oxidation reaction to the leaching solution, and raise the liquid temperature to 70-95°C; continue stirring the reaction for 15-25 minutes and then filter to achieve solid-liquid separation, and return the filtrate to the leaching process for recycling; wash the selenium powder obtained by filtration with pure water at room temperature for 2-4 times, and finally the pH of the washing water is 6.5-7.5, and the obtained product is pure selenium powder.

2. The method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology as claimed in claim 1, characterized in that: The selenium-containing material comprises elemental selenium and selenide; the selenide is one or more of H2Se, ammonium selenide, aluminum selenide, zinc selenide, arsenic selenide, antimony selenide, sodium selenide, mercury selenide, iron selenide, alkali metal selenides, and alkaline earth metal selenides.

3. The method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology as claimed in claim 1, characterized in that: In the step (2), the leaching solution is added to the stirring reaction tank, and the added volume is 65% to 75% of the tank volume.

4. The method for purifying selenium from selenium-containing materials based on alkaline hydrometallurgical technology as claimed in claim 1, characterized in that: In the step (2), the oxidation reaction is an oxidation reaction between hydrazine hydrate and H2O2 and an oxidation reaction between sodium selenide in the leaching solution and hydrazine hydrate.

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