Desulfurization smelting process of high-sulfur tin concentrate

Abstract

The invention relates to the technical field of mineral processing, in particular to a desulfurization smelting process of high-sulfur tin concentrate, which comprises the following steps: ore pretreatment: crushing, grinding and screening tin ore to obtain ore powder; culturing bacteria and inoculating, namely inoculating bacteria suitable for a high-sulfur environment into a small-scale culture tank, and culturing in a sterile environment; leaching reaction: mixing the pretreated mineral powder with water, adding a bacterial culture solution to prepare ore pulp, and leaching the ore pulp; and solution treatment and tin recovery: carrying out solid-liquid separation on the ore pulp, recovering tin metal and treating waste liquid. According to the desulfurization smelting process of the high-sulfur tin concentrate, the problems of environmental pollution and high cost existing in the traditional smelting process are effectively solved through a bacterial leaching method, and bacteria can rapidly grow and breed in a high-sulfur environment, so that the desulfurization efficiency is improved, and the production cost is reduced. The process provided by the invention is simple and convenient to operate, low in cost and environment-friendly, and the recovery rate of tin can be remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of mineral processing, and in particular to a desulfurization smelting process for high-sulfur tin concentrate. Background Art

[0002] With the continuous growth of industrial demand, the mining and utilization of high-sulfur tin concentrate has become an important issue in the mining field. However, the sulfur content in high-sulfur tin concentrate is relatively high, and traditional smelting processes are difficult to effectively remove these sulfur elements, which directly affects the purity and quality of tin metal.

[0003] At present, the commonly used high-sulfur tin concentrate desulfurization processes mainly include pyrometallurgy and hydrometallurgy. However, the pyrometallurgy process produces a large amount of sulfur dioxide gas, which not only pollutes the environment, but also threatens the health of operators; although hydrometallurgy can partially remove sulfur elements, its process is complicated, costly, and the processing efficiency is not ideal.

[0004] Therefore, there is a need for a new and efficient desulfurization smelting industry that is simple to operate, low in cost, and environmentally friendly. Summary of the invention

[0005] The main purpose of the present invention is to provide a desulfurization smelting process for high-sulfur tin concentrate, aiming to solve the problems of environmental unfriendliness and high cost in the existing desulfurization process of high-sulfur tin concentrate.

[0006] To achieve the above object, the present invention provides a desulfurization smelting process for high-sulfur tin concentrate, which comprises the following steps:

[0007] Ore pretreatment: crushing, grinding and screening the tin ore to obtain ore powder;

[0008] Cultivate bacteria and inoculate, select bacteria suitable for high sulfur environment, inoculate into small-scale culture tanks and culture under sterile environment;

[0009] Leaching reaction, mixing the pretreated mineral powder with water, adding bacterial culture solution to make a slurry, and leaching the slurry;

[0010] Solution treatment and tin recovery: recover tin metal and treat waste liquid after solid-liquid separation of slurry.

[0011] Furthermore, the steps of culturing bacteria and inoculating, selecting bacteria suitable for high-sulfur environments, inoculating them into small-scale culture tanks, and culturing them in a sterile environment include:

[0012] Bacterial strain culture: initially culture the bacterial strains suitable for high-sulfur environments in small-scale culture media to ensure the activity and purity of the strains;

[0013] Preparation of culture medium: preparing culture medium containing nitrogen source, phosphorus source and trace elements and sterilizing the culture medium at high temperature to eliminate miscellaneous bacteria;

[0014] Bacterial inoculation: inoculate the bacteria into the sterilized culture medium under a sterile environment;

[0015] Bacterial culture, using constant temperature equipment to stabilize the temperature in the culture medium and controlling the pH value of the culture medium through acid or alkali solution;

[0016] Bacterial concentration monitoring: regularly take samples from the culture medium to test the bacterial concentration to ensure that the bacterial concentration reaches 10 7 ~10 9 Pieces / ml.

[0017] Furthermore, the ore pretreatment, the step of crushing, grinding and screening the tin ore to obtain ore powder includes:

[0018] The tin ore is sent to the jaw crusher for primary crushing, and the ore is crushed into ore particles with a diameter of 50-100mm;

[0019] The ore particles after primary crushing are sent to the cone crusher for secondary crushing, and the ore particles are crushed to a diameter of 10-20 mm;

[0020] The ore particles after secondary crushing are further ground into ore fine powder with a diameter of 75 to 150 μm using a ball mill;

[0021] The fine ore powder after grinding is sent to the vibrating screen for screening.

[0022] Furthermore, in the leaching reaction, the pretreated mineral powder is mixed with water, and a bacterial culture solution is added to prepare a slurry. The steps of leaching the slurry include:

[0023] The pretreated ore fine powder is mixed with water at a solid-liquid ratio of 1:3 to 1:5 to form a slurry;

[0024] Add the cultured thiobacillus oxidans into the ore pulp at a ratio of 5 to 10% of the ore pulp volume;

[0025] Use an efficient agitator to fully mix the slurry and bacteria to ensure that the bacteria are evenly distributed;

[0026] Maintain a stable environment for the slurry and bacterial mixture and circulate the slurry regularly during the leaching reaction.

[0027] Furthermore, the step of maintaining a stable environment of the slurry and the bacterial mixture and regularly circulating the slurry during the leaching reaction also includes:

[0028] pH value control: by adding acid or alkali solution, the pH value of the mixture of slurry and bacteria is maintained between 1.5 and 2.5;

[0029] Oxygen quantity control, through aeration devices and oxygen supply equipment, to ensure that there is sufficient oxygen supply in the slurry;

[0030] The reaction time is regulated to maintain the leaching reaction time at 7 to 30 days, and the slurry is circulated regularly.

[0031] Furthermore, the solution treatment and tin recovery step of separating the slurry into solid and liquid, recovering the tin metal and treating the waste liquid further comprises:

[0032] Solid-liquid separation: using a solid-liquid separation device to separate the leached slurry into solid and liquid;

[0033] Washing: washing the solid residue after solid-liquid separation with clean water;

[0034] Tin recovery, which recovers tin metal by chemical precipitation, electrolytic recovery or solvent extraction;

[0035] Waste liquid treatment, waste liquid is treated by neutralization, sedimentation and filtration.

[0036] Furthermore, the bacteria suitable for use in high-sulfur environments are at least one of Thiobacillus thiooxidans and Thiobacillus thiobacillus.

[0037] The present invention provides a desulfurization smelting process for high-sulfur tin concentrate, which effectively solves the environmental pollution and high cost problems existing in the traditional smelting process through the bacterial leaching method, and improves the desulfurization efficiency by virtue of the fact that bacteria can grow and reproduce rapidly in a high-sulfur environment. The process proposed by the present invention is simple to operate, low in cost and environmentally friendly, and can significantly improve the recovery rate of tin. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0040] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] The desulfurization process involved in the present invention adopts a bacterial leaching method, which uses specific sulfur-oxidizing bacteria to oxidize the sulfide in the ore and convert it into soluble sulfate, thereby achieving desulfurization. These bacteria release acidic substances through metabolic processes, promoting the dissolution and oxidation of sulfide.

[0042] Among them, the constant temperature equipment for initial culture in the present invention controls the culture temperature at 28-32°C, and the culture is carried out in a sterile environment. The formula of the culture medium includes: 0.4g / L (NH4)2SO4, 0.1g / L K2HPO4, 0.5g / L MgSo4·7H2O, 0.01g / L CaCl2, and the pH value is adjusted to 2.0.

[0043] In detail, during bacterial inoculation, the initially cultured bacteria are inoculated into the sterilized culture medium at a ratio of 5 to 10% using a sterile pipette or inoculation loop to ensure uniform distribution of the bacteria and avoid bacterial aggregation. The acid used in the bacterial culture process is dilute sulfuric acid, and the alkali used is sodium hydroxide solution to ensure uniform distribution of bacteria and nutrients. In addition, the gas flow rate needs to be controlled at 0.2 to 0.5 vvm (volume gas / volume liquid / minute), and samples are taken every 24 hours to monitor the growth of bacteria. The bacterial concentration is detected by microscope counting or optical density meter (OD600) to ensure that the bacterial concentration reaches 10 7 ~10 9 Pieces / ml.

[0044] During bacterial inoculation, the cultured bacteria are inoculated into the slurry at 5-10% of the slurry volume, and the slurry is placed in a stirring device and continuously stirred to ensure that the bacteria are evenly distributed in the slurry. The stirring time is 30-60 minutes to ensure that the ore and the bacteria are fully in contact.

[0045] In the present invention, the primary crushing usually uses a jaw crusher or a gyratory crusher to crush large pieces of raw ore into smaller pieces, usually with a diameter of 50 to 100 mm. A cone crusher or an impact crusher is used to further reduce the ore particles after the primary crushing to 10 to 20 mm. Finally, a vibrating screen or a rotary screen is used to screen the ore particles according to size to ensure that most of the particles are within a diameter of 10 to 20 mm. If there are ore particles exceeding this range, they are returned to the secondary crushing equipment for re-crushing.

[0046] In detail, limiting the ore particles to 10-20 mm helps improve grinding efficiency and increase the surface area of ​​the leaching reaction, which is beneficial for full contact between bacteria and ore, enhancing the efficiency and effect of leaching, while also facilitating the subsequent separation and purification process and improving the stability and efficiency of the overall process.

[0047] Among them, in order to further improve the efficiency and effect of the leaching reaction, the present invention has carried out fine control of key parameters such as temperature, pH value, aeration, stirring, etc. during the bacterial leaching process, and introduced periodic reaction and circulating flow technology.

[0048] In detail, in the present invention, ore particles are mixed with water at a solid-liquid ratio of 1:3 to 1:5 to form a slurry, and the slurry is transferred to a leaching tank. At the same time, a constant temperature device is used to control the temperature of the leaching tank at 30 to 35°C, which is the most suitable temperature range for the growth and activity of Thiobacillus thiooxidans. A temperature sensor can also be installed to monitor the temperature in the leaching tank in real time to ensure that the temperature fluctuates within ±1°C, thereby not affecting the growth of bacteria.

[0049] The present invention can also control the pH value between 1.8 and 2.2 by adding dilute sulfuric acid or sodium hydroxide solution to ensure the stability of the pH value of the bacterial growth environment. It can also use efficient aeration equipment to introduce oxygen into the slurry to ensure sufficient oxygen concentration. During the leaching reaction, a mechanical stirring device can be used to stir at a speed of 150 to 250 per minute, and the slurry can be pumped out from the bottom of the leaching tank by a liquid pump and then refluxed from the top of the leaching tank to form a circulating flow, thereby enhancing the uniformity of the slurry and the contact efficiency of the bacteria.

[0050] In detail, in the present invention, a filter press or a centrifuge is used to perform solid-liquid separation on the leached slurry to obtain a tin-containing solution and a solid residue. After the solid-liquid separation, the solid residue after the solid-liquid separation is washed with clean water, and the residual tin-containing solution is further recovered. The tin metal is recovered from the obtained tin-containing solution by chemical precipitation, electrolytic recovery or solvent extraction recovery, and the waste liquid generated in the process is treated by neutralization, sedimentation and filtration.

[0051] In the present invention, the tin-containing solution obtained after the leaching reaction is recovered by electrolytic recovery, wherein the tin-containing solution is placed in an electrolytic cell, a chloride electrolytic agent (such as potassium chloride, sodium chloride, etc.) is poured into the mixture, and then an electric current is applied to the mixed solution. During the electrolysis process, the anode loses electrons to generate chlorine gas, and the cathode absorbs electrons to reduce tin ions to metallic tin, thereby achieving efficient reduction of tin ions to metallic tin.

[0052] Among them, the present invention has the following application embodiments:

[0053] Embodiment 1:

[0054] 1. Ore pretreatment, crushing high-sulfur tin concentrate to less than 75μm;

[0055] 2. Cultivate bacteria and inoculate, using Thiobacillus thiooxidans, and culture at 30°C for 5 days;

[0056] 3. Leaching reaction: add the bacterial culture solution into the slurry at 10% of the total volume of the slurry, and control the pH value at 2.0, and leach for 20 days;

[0057] 4. Solution treatment and tin recovery: Pour the tin-containing solution into a sodium chloride electrolytic cell, stir and mix thoroughly, and pass an electric current to obtain metallic tin.

[0058] Embodiment 2:

[0059] 1. Ore pretreatment, crushing high-sulfur tin concentrate to less than 100μm;

[0060] 2. Cultivate bacteria and inoculate, using Thiobacillus thiooxidans, and culture at 28°C for 7 days;

[0061] 3. Leaching reaction: add the bacterial culture solution to the slurry at 7% of the total volume of the slurry, and control the pH value at 1.8. Leaching reaction for 25 days;

[0062] 4. Solution treatment and tin recovery: Pour the tin-containing solution into a sodium chloride electrolytic cell, stir and mix thoroughly, and pass an electric current to obtain metallic tin.

[0063] Embodiment 3:

[0064] 1. Ore pretreatment, crushing high-sulfur tin concentrate to less than 150μm;

[0065] 2. Cultivate bacteria and inoculate, using Thiobacillus thiooxidans, and culture at 32°C for 6 days;

[0066] 3. Leaching reaction: add the bacterial culture solution into the slurry at 5% of the total volume of the slurry, and control the pH value at 2.2. Leaching reaction for 30 days;

[0067] 4. Solution treatment and tin recovery: Recover tin metal by electrolysis. Pour the tin-containing solution into a sodium chloride electrolytic cell, stir and mix thoroughly, and pass an electric current to obtain metallic tin.

[0068] Comparative Example 1:

[0069] 1. Ore pretreatment, crushing high-sulfur tin concentrate to less than 100μm;

[0070] 2. Tin concentrate reduction smelting: the crushed ore is mixed with coal coke and then put into the Ausmelt furnace and heated to 232°C to reduce the tin oxide in the tin concentrate to crude tin;

[0071] 3. Fire refining of crude tin, heating the crude tin from 232°C to 596°C in multiple stages, separating the tin in the crude tin from most of the metal impurities, and obtaining liquid refined tin containing a small amount of metal impurities;

[0072] 4. The liquid refined tin is cooled to generate crystal suspensions of impurity metals such as Fe-As solid compounds and copper sulfide. The crystal suspensions are suspended on the liquid refined tin to form scum. Sawdust is added to promote the condensation and floating of the impurity metal grains, and the scum is removed.

[0073] 5. Repeat adding sawdust and removing scum until no more scum is precipitated, and cool the liquid refined tin to obtain refined tin.

[0074] Comparative Example 2:

[0075] 1. Ore pretreatment: crush the high-sulfur tin concentrate to less than 100μm through multi-stage crushing, filtration and screening;

[0076] 2. The crushed ore particles are sent to a 3 mol / L dilute hydrochloric acid solution for leaching reaction. The leaching time is 3 hours and the temperature is 70°C to obtain an acid leaching solution containing tin;

[0077] 3. Separate the acid leaching solution from the solid residue by filtering to obtain a clear acid leaching solution;

[0078] 4. Recover tin metal by electrolysis. Pour the clear acid leaching solution containing tin into a sodium chloride electrolytic cell and stir it thoroughly. Then, apply power to the sodium chloride electrolytic cell. The tin ions are reduced to metallic tin and deposited on the cathode to obtain metallic tin.

[0079] Among them, the conventional smelting method of pyrometallurgy was adopted in Comparative Example 1, and the conventional smelting method of hydrometallurgy was adopted in Comparative Example 2. The pyrometallurgy in Comparative Example 1 is to heat the tin ore at high temperature to melt the tin in the tin ore, and then obtain tin metal by reducing the tin element. The main process flow includes roasting, reduction, and refining, wherein roasting is to oxidize the sulfide in the tin ore into oxide to improve the grade of the tin ore, and then reduce the tin oxide into metallic tin by reduction, and finally remove the impurities in the metallic tin by refining to obtain pure tin. The hydrometallurgy in Comparative Example 2 is to dissolve the tin in the tin ore by chemical solvent, and then precipitate the tin by chemical reaction to obtain tin metal.

[0080] Tin recovery rate and tin purity detection experiment:

[0081] The materials of Examples 1-3 and Comparative Examples 1-2 were selected as samples to test the tin recovery rate and tin purity. The specific experimental steps are as follows:

[0082] (I) Tin recovery rate test

[0083] step:

[0084] S1. Weigh 1g of tin metal;

[0085] S2. Dissolve tin metal in 10 ml of 1 mol / L dilute hydrochloric acid and stir until the tin metal is completely dissolved;

[0086] S3, dilute the dissolved sample solution to 100 ml;

[0087] S4. Determine the concentration of tin (mg / L) in the solution using an inductively coupled plasma mass spectrometer (ICP-MS);

[0088] S5. Calculate the actual total amount of tin according to the measured tin concentration, and convert it into a tin recovery rate, wherein the calculation formula of the tin recovery rate is (actual total amount of tin / theoretical total amount of tin)*100%.

[0089] (II) Tin purity test

[0090] step:

[0091] S1. Weigh 1g of tin metal;

[0092] S2. Dissolve tin metal in 10 ml of 1 mol / L dilute hydrochloric acid and stir until the tin metal is completely dissolved;

[0093] S3, dilute the dissolved sample solution to 100 ml;

[0094] S4. Determine the concentration of tin (mg / L) and the concentration of other impurity metals (mg / L) in the solution using an inductively coupled plasma mass spectrometer (ICP-MS);

[0095] S5. Calculate the tin purity according to the purity formula, wherein tin purity = (tin concentration / total metal concentration)*100%.

[0096] Table 1 Tin recovery rate and tin purity test data

[0097]

[0098] Experimental conclusion:

[0099] Through the experimental data of the above three groups of embodiments and two groups of control embodiments, it can be seen that the bacterial leaching method adopted in the present invention can desulfurize high-sulfur tin concentrate, has a high tin recovery rate and purity, and can also reduce energy consumption and reduce environmental pollution, which proves the effectiveness and feasibility of the bacterial leaching method in the desulfurization smelting process of high-sulfur tin concentrate.

[0100] In combination with all the above embodiments, the desulfurization smelting process of a high-sulfur tin concentrate provided by the present invention effectively solves the environmental pollution and high cost problems existing in the traditional pyrometallurgical and hydrometallurgical smelting processes through the bacterial leaching method. In the present invention, through the bacterial culture and inoculation technical scheme, the bacteria can grow and reproduce rapidly in a high-sulfur environment, thereby improving the desulfurization efficiency. By controlling the temperature, pH value and ventilation volume, the activity of the bacteria is maximized, and the removal rate of sulfur element is significantly improved. In addition, the process is simple to operate, low-cost, environmentally friendly, and can significantly improve the recovery rate of tin to more than 85%, with good industrial application prospects and economic benefits.

[0101] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A desulfurization smelting process for high-sulfur tin concentrate, characterized in that: The following steps are involved: Ore pretreatment: crushing, grinding and screening the tin ore to obtain ore powder; Cultivate bacteria and inoculate, select bacteria suitable for high sulfur environment, inoculate into small-scale culture tanks and culture under sterile environment; Leaching reaction, mixing the pretreated mineral powder with water, adding bacterial culture solution to make a slurry, and leaching the slurry; Solution treatment and tin recovery: recover tin metal and treat waste liquid after solid-liquid separation of slurry.

2. The desulfurization smelting process of high-sulfur tin concentrate according to claim 1, characterized in that: The steps of culturing bacteria and inoculating, selecting bacteria suitable for high-sulfur environments, inoculating them into small-scale culture tanks, and culturing them in a sterile environment include: Bacterial strain culture: initially culture the bacterial strains suitable for high-sulfur environments in small-scale culture media to ensure the activity and purity of the strains; Preparation of culture medium: preparing culture medium containing nitrogen source, phosphorus source and trace elements and sterilizing the culture medium at high temperature to eliminate miscellaneous bacteria; Bacterial inoculation: inoculate the bacteria into the sterilized culture medium under a sterile environment; Bacterial culture, using constant temperature equipment to stabilize the temperature in the culture medium and controlling the pH value of the culture medium through acid or alkali solution; Bacterial concentration monitoring: regularly take samples from the culture medium to test the bacterial concentration to ensure that the bacterial concentration reaches 10 7 ~10 9 Pieces / ml.

3. The desulfurization smelting process of high-sulfur tin concentrate according to claim 1, characterized in that: The ore pretreatment, the steps of crushing, grinding and screening the tin ore to obtain ore powder, include: The tin ore is sent to the jaw crusher for primary crushing, and the ore is crushed into ore particles with a diameter of 50-100mm; The ore particles after primary crushing are sent to the cone crusher for secondary crushing, and the ore particles are crushed to a diameter of 10-20 mm; The ore particles after secondary crushing are further ground into ore fine powder with a diameter of 75 to 150 μm using a ball mill; The fine ore powder after grinding is sent to the vibrating screen for screening.

4. The desulfurization smelting process of high-sulfur tin concentrate according to claim 1, characterized in that: The leaching reaction comprises mixing the pretreated mineral powder with water, adding bacterial culture solution to prepare mineral slurry, and the steps of leaching the mineral slurry include: The pretreated ore fine powder is mixed with water at a solid-liquid ratio of 1:3 to 1:5 to form a slurry; Add the cultured thiobacillus oxidans into the ore pulp at a ratio of 5 to 10% of the ore pulp volume; Use an efficient agitator to fully mix the slurry and bacteria to ensure that the bacteria are evenly distributed; Maintain a stable environment for the slurry and bacterial mixture and circulate the slurry regularly during the leaching reaction.

5. The desulfurization smelting process of high-sulfur tin concentrate according to claim 4, characterized in that: The step of maintaining a stable environment of the slurry and bacterial mixture and regularly circulating the slurry during the leaching reaction also includes: pH value control: by adding acid or alkali solution, the pH value of the mixture of slurry and bacteria is maintained between 1.5 and 2.5; Oxygen quantity control, through aeration devices and oxygen supply equipment, to ensure that there is sufficient oxygen supply in the slurry; The reaction time is regulated to maintain the leaching reaction time at 7 to 30 days, and the slurry is circulated regularly.

6. The desulfurization smelting process of high-sulfur tin concentrate according to claim 5, characterized in that: The solution treatment and tin recovery step of recovering tin metal after solid-liquid separation of the slurry and treating the waste liquid also includes: Solid-liquid separation: using a solid-liquid separation device to separate the leached slurry into solid and liquid; Washing: washing the solid residue after solid-liquid separation with clean water; Tin recovery, which recovers tin metal by chemical precipitation, electrolytic recovery or solvent extraction; Waste liquid treatment, waste liquid is treated by neutralization, sedimentation and filtration.

7. The desulfurization smelting process of high-sulfur tin concentrate according to claim 1, characterized in that: The bacteria suitable for use in a high-sulfur environment are at least one of Thiobacillus thiooxidans and Thiobacillus thiobacillus.

Images