Method for recovering tungsten from tungsten smelting soda boiling slag through reselection

Abstract

The invention belongs to the technical field of tungsten smelting, and particularly discloses a method for recycling tungsten from tungsten smelting soda boiling slag through reselection, tungsten in the slag is recycled through a physical mineral separation method, a large number of acid-base reagents are not introduced, acid-base wastewater is not generated, and high-energy-consumption roasting or high-temperature acid-base leaching is not needed. The process is simple, large-scale treatment can be achieved, reagent consumption is low, energy consumption is low, closed-loop circulation of mineral separation water can be achieved, no wastewater is discharged, the process is environmentally friendly and free of pollution risks, meanwhile, indexes of the soda boiling residues subjected to innocent treatment can reach industrial solid waste, hazardous waste is converted into common solid waste, and the economic benefit is high. The environment-friendly treatment cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of tungsten smelting, and specifically discloses a method for recovering tungsten by gravity separation of tungsten smelting alkali-boiling slag. Background Art

[0002] my country ranks first in the world in tungsten resource reserves, production, and export volume. Depending on the type of tungsten ore raw material, ammonium paratungstate (AMPT) is mainly produced using a sodium-alkali autoclave-ion exchange / alkaline extraction-deep molybdenum removal-evaporation crystallization process. During the sodium-alkali autoclave process of tungsten smelting, a large amount of tungsten-containing alkali slag, also known as alkali-boiled tungsten slag or waste tungsten slag, is produced. Based on an APT production target of 130,000 tons in 2024, the annual output is approximately 100,000-120,000 tons. Alkali slag is primarily composed of iron, manganese, and calcium oxides. It also contains high-value metallic elements such as W, Sn, Ta, Nb, and Sc, as well as harmful elements such as As, Pb, Cr, and F. Due to its high As content and leaching toxicity, the Ministry of Environmental Protection listed "alkaline slag (tungsten slag) produced by alkali decomposition during the production of ammonium paratungstate" on the National List of Hazardous Wastes in 2016. Therefore, under the dual pressures of comprehensive resource utilization and environmental protection, how to achieve the reduction, resource utilization, and harmless disposal of tungsten slag is of great significance to the sustainable development of my country's tungsten smelting industry.

[0003] Due to the limitations of the process level of tungsten smelting units, the WO3 content in alkali-boiled tungsten slag ranges from 0.5% to 5%, resulting in a waste of about 2,000-3,000 tons of tungsten metal resources each year. At present, the soda high-temperature sintering method + water immersion method is commonly used to treat the alkali-boiled tungsten slag, which can reduce the WO3 content in the slag to below 0.5%. However, the amount of soda consumed in the process is very high, the roasting process consumes a lot of energy, and the environmental protection treatment costs of waste gas and wastewater are high; there is also a secondary high-temperature alkali pressure boiling process to treat the waste tungsten slag, which can reduce the tungsten content of the waste tungsten slag from 3% to 0.5-1%, but similar to the soda high-temperature sintering method, this method also has the disadvantages of excessive alkali consumption and high energy consumption; in addition, the alkaline process has high energy consumption and large alkali consumption in the process of recovering tungsten from the alkaline-boiled slag, and is usually only suitable for treating high-grade tungsten slag with a WO3 content of 3% to 6%.

[0004] Some tungsten smelting units have explored the use of acid technology at room temperature and pressure, using hydrochloric acid and sulfur-phosphorus mixed acid to recover tungsten from tungsten slag. After leaching, weak alkaline anion resin is used to enrich and remove impurities, and the tungsten content in the slag is reduced to 0.5-1%. However, since the grade of tungsten in tungsten slag is lower than that of tungsten concentrate, whether acid or alkaline technology is used for tungsten recovery, a large amount of acid and alkali reagents are required. The enrichment of low-concentration tungsten solution is accompanied by a large amount of wastewater and exhaust gas that require environmental treatment, and the cost is relatively high. Summary of the Invention

[0005] In order to solve the problems in the background technology, the present invention discloses a method for recovering tungsten by gravity selection from tungsten smelting alkali-boiling slag, which utilizes the differences in physical properties such as particle size and density of the alkali-boiling slag to recover tungsten by gravity selection, and adopts a physical mineral processing method to recover tungsten from the alkali-boiling slag. The required reagents are small, the process operation is simple, and the processing cost is low. At the same time, the tungsten slag is harmlessly disposed of to realize the conversion of hazardous waste into general solid waste.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0007] A method for recovering tungsten by gravity separation of tungsten smelting alkali-boiling slag, characterized by comprising the following steps:

[0008] (1) The tungsten smelting alkali-boiling slag is mixed with ore to prepare pulp, and an oxidizing dispersant and a defoaming agent are added during the pulping process;

[0009] (2) wet screening or hydrocyclone classification of the slurry obtained in step (1) to obtain coarse particles and fine particles;

[0010] (3) the fine particles obtained in step (2) are separated and enriched by a blanket concentrator to obtain coarse concentrate and coarse tailings;

[0011] (4) The coarse particles obtained in step (2) and the coarse concentrate obtained in step (3) are mixed and subjected to secondary separation and enrichment using a shaking table to obtain shaken concentrate, shaken middlings and shaken tailings, respectively. The shaken concentrate is subjected to filter pressing to obtain low-grade tungsten concentrate, the low-grade tungsten concentrate is returned to the tungsten smelting process, and the shaken middlings are returned to the shaking table for further separation;

[0012] (5) The shaking tailings obtained in step (4) are swept and selected by a blanket concentrator to obtain sweep concentrate and sweep tailings, and the sweep concentrate is returned to step (4) to continue to be sorted and enriched by a shaking table;

[0013] (6) The coarse tailings obtained in step (3) and the swept tailings obtained in step (5) are combined, and after adjusting the pH, heavy metal removers and flocculants are added for harmless disposal, and then filtered to obtain industrial solid waste and filter press circulating water. The filter press circulating water is allowed to settle and then returned to the slurry preparation process for closed-loop circulation.

[0014] Furthermore, in the method for recovering tungsten by gravity selection of tungsten smelting alkali-boiling slag, in step (1), the content of WO3 in the tungsten smelting alkali-boiling slag is 0.5-5%, the mass percentage content of WO3 is controlled to change within ±0.5% during the ore blending process, and the mass percentage concentration of the tungsten smelting alkali-boiling slag slurry is adjusted to 10-20%.

[0015] Furthermore, in the method for recovering tungsten by gravity selection of tungsten smelting alkali-boiling slag, the oxidizing dispersant is an inorganic sulfate, the addition amount of which is 0.5-2‰ of the ore amount, and the defoaming agent is an organosilicon defoaming agent for mineral processing, the addition amount of which is 0.5-2kg / t.

[0016] Furthermore, in the method for recovering tungsten by gravity separation of tungsten smelting alkali-boiling slag, step (2) adopts a 120-325 mesh screen to wet screen or pre-classify with a hydrocyclone according to the particle size of the alkali-boiling slag, the mass of the coarse particles is 10-30% of the mass of the total slurry, and the WO3 grade enrichment ratio in the coarse particles is 1.5-3.

[0017] Furthermore, in the method for recovering tungsten by gravity selection of tungsten smelting alkali-boiling slag, the number of series stages of blanket beneficiation in step (3) and step (5) is 3-10, the mass percentage concentration of the selected ore pulp is 10-20%, and the WO3 grade enrichment ratio of the concentrate in step (3) roughing and step (5) scavenging is 1.2-3, respectively.

[0018] Furthermore, in the method for recovering tungsten by gravity separation of tungsten smelting alkali-boiling slag, the mass percentage concentration of the slurry entering the shaking table in step (4) is 15-30%, and the grade of the obtained low-grade tungsten concentrate is 10-30%.

[0019] Furthermore, in the method for recovering tungsten by gravity separation of tungsten smelting alkali-boiling slag, step (6) harmless disposal refers to adding sulfuric acid, nitric acid, oxalic acid or organic acid to the tailings to adjust the pH value to 6-9, adding heavy metal remover ferrous sulfate and fluorine remover PAC according to the difference in heavy metal pollution and toxicity in the alkali-boiling slag to remove harmful elements such as As, Pb, Cr, and F, adding an appropriate amount of oxidant ammonium persulfate or hydrogen peroxide according to the content of arsenic and chromium in the alkali-boiling slag after treatment to react and precipitate to remove the excess arsenic, and finally adding PAM for two-stage dense flocculation, and after harmless disposal, the tungsten slag slurry is filtered to obtain industrial solid waste and filter-pressed circulating water, so that the alkali-boiling slag becomes an industrial waste without hazardous characteristics, and the filter-pressed circulating water is returned to the system for recycling after sedimentation and standing. When the tungsten in the circulating water reaches a certain concentration, it is recovered by ion exchange and then evaporated.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The method for recovering tungsten by gravity separation of tungsten smelting alkali-boiling slag adopts a physical mineral separation method to recover tungsten in the slag, does not introduce a large amount of acid and alkali reagents, does not generate acid and alkali wastewater, does not require high-energy consumption roasting or high-temperature acid and alkali leaching, and utilizes physical differences such as particle size and density of the alkali-boiling slag to recover tungsten by gravity separation. The process is simple and can be processed on a large scale, with low reagent consumption and low energy consumption, and the ore dressing water can be closed-loop circulated without wastewater discharge. The process is environmentally friendly and has no pollution risk. The alkali-boiling slag can meet the indicators of industrial solid waste after harmless treatment, and the environmental protection disposal cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 The present invention is a process flow chart of a method for recovering tungsten by gravity selection of tungsten smelting alkali-boiling slag. DETAILED DESCRIPTION

[0024] In order to better understand the present invention, the content of the present invention is further clearly set forth below in conjunction with the examples, but the protection content of the present invention is not limited to the following examples. In the following description, a large number of specific details are provided in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0025] Example 1

[0026] In this example, the raw material is soda-boiled scheelite slag, the tungsten content in the form of WO3 is 0.94% (mass percentage), and the main components are mineral phases such as calcium tungstate, iron tungstate, calcium carbonate, calcium phosphate, silicon dioxide, and calcium fluoride.

[0027] Step (1): adding circulating water to the alkali-boiled tungsten slag after pressure filtration to prepare a slurry with a slurry concentration of 14-18%, and adding a sulfate oxidizing dispersant with a ore content of 1‰ and a mineral processing defoamer with a content of 0.5-2kg / t. The amount of the mineral processing defoamer is adjusted according to the foaming situation. After the slurry is prepared, the slurry is dispersed by basket filtration to remove particulate matter.

[0028] Step (2): screening the slurry through a 200-mesh wet sieve, pre-sorting the coarse and fine particles to obtain coarse particles and fine particles, wherein the coarse particles account for about 15-30% and the tungsten content enrichment ratio is about 2;

[0029] Step (3): the fine particle concentration in step (2) is controlled at 13-17%, and 5-stage blankets are recycled in series to obtain coarse concentrate and coarse tailings, wherein the tungsten content enrichment ratio of the coarse concentrate is 1.5-2.5, and the tungsten content of the coarse tailings is less than 0.4%;

[0030] Step (4): the coarse particles in step (2) and the coarse concentrate in step (3) are fed into different shaking tables respectively, and the mass percentage concentration of the selected slurry is 15-20%, thereby obtaining a low-grade tungsten shaking concentrate with a tungsten content of 15-20%. The actual tungsten recovery rate based on the shaking concentrate is 44.8%, and the medium ore is returned to the shaking table for further separation;

[0031] Step (5): The tailings in step (4) are fed into a 5-stage series sweeping blanket to obtain sweep concentrate and sweep tailings, wherein the sweep concentrate has a tungsten enrichment ratio of 1.5-2.5 and the sweep tailings have a tungsten content of less than 0.5%;

[0032] Step (6): The coarse tailings obtained in step (3) and the swept tailings slurry obtained in step (5) are combined, sulfuric acid is added to adjust the pH value to 8-9, ferrous sulfate and PAC are added to remove harmful elements such as As, Pb, Cr, and F, and the tailings are filtered after PAM flocculation. The tungsten content in the filter press residue is less than 0.5%, and the leaching toxicity is less than the relevant requirements of the national standard GB5085. At the same time, the turbidity of the filter press water is less than 200 NTU after standing and is returned for leaching.

[0033] Example 2

[0034] In this example, the raw material is soda-boiled scheelite slag, the tungsten content in the form of WO3 is 1.59% (mass percentage), and the main components are mineral phases such as calcium tungstate, iron tungstate, calcium carbonate, calcium phosphate, silicon dioxide, and calcium fluoride.

[0035] Step (1): adding circulating water to the alkali-boiled tungsten slag after pressure filtration to adjust the slurry to a slurry concentration of 13-18%, and adding a sulfate dispersant and a mineral processing defoamer. The feeding amount of the sulfate dispersant is 1‰ of the ore amount, and the feeding amount of the mineral processing defoamer is 0.5-2kg / t. The feeding amount of the mineral processing defoamer is adjusted according to the foaming situation. After slurry adjustment, the basket filtration is dispersed to remove particulate matter.

[0036] Step (2): The slurry is pre-sorted into coarse and fine particles using a hydrocyclone to obtain coarse particles and fine particles, wherein coarse particles larger than 200 meshes account for about 20-30%, and the tungsten content enrichment ratio is greater than 1.5;

[0037] Step (3): the fine particle concentration in step (2) is controlled at 13-17%, and 5-stage blankets are recycled in series to obtain coarse concentrate and coarse tailings, wherein the tungsten content enrichment ratio of the coarse concentrate is 1.2-2.5, and the tungsten content of the coarse tailings is less than 0.5%;

[0038] Step (4): the coarse particles in step (2) and the coarse concentrate in step (3) are respectively put into different shaking tables for classification, with a concentration of 15-20%, to obtain a low-grade tungsten concentrate with a tungsten content of 15-25%. The actual tungsten recovery rate based on the concentrate is 59.7%, and the medium ore is returned to the shaking table for further sorting;

[0039] Step (5): in step (4), the tail is shaken into 10 stages of series sweeping blankets to obtain sweep concentrate and sweep tailings, the sweep concentrate has a tungsten enrichment ratio of 1.5-2.5, and the sweep tailings has a tungsten content of less than 0.6%;

[0040] Step (6): adding sulfuric acid to the crude tailings of step (3) and the swept tailings slurry of step (5) to adjust the pH value to less than 9, adding ferrous sulfate + PAC to remove heavy metals and fluorine, and performing PAM flocculation precipitation. After the tailings are filtered, the tungsten content in the filter residue is less than 0.5%, the leaching toxicity is less than the relevant requirements of the national standard GB5085, and the turbidity of the filter water after standing is less than 200 NTU and is returned for leaching.

[0041] Example 3

[0042] The raw materials of Example 3 are the same as those of Example 1, and steps (1) to (5) of Example 3 are the same as those of Example 1;

[0043] Step (6): The coarse tailings obtained in step (3) and the swept tailings slurry obtained in step (5) are combined, sulfuric acid is added to adjust the pH value to 8-9, and a ferrous sulfate + PAC mixed solution is prepared with the returned circulating water, the ferrous sulfate dosage is 1.5-2% of the ore amount, the PAC dosage is 0.7-2‰ of the ore amount, and the solution concentration is 5-10%. After mixing with the tailings slurry pipeline, react, and add ammonium persulfate or hydrogen peroxide oxidant depending on the content of arsenic and chromium elements to achieve precipitation and removal of heavy metals As, Pb, Cr and fluorine. 1‰ PAM (the dosage is adjusted depending on the flocculation water purification situation) is prepared and added to a two-stage thickener for flocculation and allowed to stand. After thickening, the bottom flow is filtered, the tungsten content in the filter press residue is less than 0.5%, and the filter press residue leaching toxicity test is less than the relevant requirements of the national standard GB5085. At the same time, the turbidity of the filter press water and the two-stage thickening overflow water after standing is less than 200NTU and returned for leaching.

[0044] Example 4

[0045] In this example, the raw material is soda-boiled scheelite slag, the tungsten content in the form of WO3 is 4.58% (mass percentage), and the main components are mineral phases such as calcium tungstate, iron tungstate, calcium carbonate, calcium phosphate, silicon dioxide, and calcium fluoride.

[0046] Step (1): adding circulating water to the alkali-boiled tungsten slag after pressure filtration to adjust the slurry to a slurry concentration of 13-18%, and adding a sulfate dispersant and a mineral processing defoamer. The feeding amount of the sulfate dispersant is 1‰ of the ore amount, and the feeding amount of the mineral processing defoamer is 0.5-2kg / t. The feeding amount of the mineral processing defoamer is adjusted according to the foaming situation. After slurry adjustment, the basket filtration is dispersed to remove particulate matter.

[0047] Step (2): The slurry is pre-sorted into coarse and fine particles using a hydrocyclone to obtain coarse particles and fine particles, wherein coarse particles larger than 200 meshes account for about 20-30%, and the tungsten content enrichment ratio is greater than 1.5;

[0048] Step (3): the fine particle concentration in step (2) is controlled at 13-17%, and 5-stage blankets are recycled in series to obtain coarse concentrate and coarse tailings, wherein the tungsten content enrichment ratio of the coarse concentrate is 1.2-2.5, and the tungsten content of the coarse tailings is less than 0.6%;

[0049] Step (4): the coarse particles in step (2) and the coarse concentrate in step (3) are respectively put into different shaking tables for classification, with a concentration of 13-20%, to obtain a low-grade tungsten concentrate with a tungsten content of 15-25%. The actual tungsten recovery rate based on the concentrate is 82.4%, and the medium ore is returned to the shaking table for further sorting;

[0050] Step (5): in step (4), the tail is shaken into 10 stages of series sweeping blankets to obtain sweep concentrate and sweep tailings, the sweep concentrate has a tungsten enrichment ratio of 1.2-2.5, and the sweep tailings has a tungsten content of less than 0.8%;

[0051] Step (6): adding sulfuric acid to the crude tailings of step (3) and the swept tailings slurry of step (5) to adjust the pH value to less than 9, adding ferrous sulfate + PAC to remove heavy metals and fluorine, and PAM flocculation precipitation. After the tailings are filtered, the tungsten content in the filter residue is less than 0.8%, the leaching toxicity is less than the relevant requirements of the national standard GB5085, and the turbidity of the filter water after standing is less than 200 NTU and is returned for leaching.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limiting. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for recovering tungsten from tungsten smelting alkali-boiling slag by gravity separation, characterized by: The steps include: (1) The tungsten smelting alkali-boiling slag is mixed with ore to prepare pulp, and an oxidizing dispersant and a defoaming agent are added during pulping; (2) The slurry obtained in step (1) is subjected to wet screening or hydrocyclone classification to pre-sort the slurry into coarse particles and fine particles; (3) The fine particles obtained in step (2) are sorted by a blanket concentrator to obtain coarse concentrate and coarse tailings; (4) The coarse particles obtained in step (2) and the coarse concentrate obtained in step (3) are mixed and subjected to secondary separation and enrichment using a shaking table to obtain shaken concentrate, shaken middlings and shaken tailings, respectively. The shaken concentrate is subjected to filter pressing to obtain low-grade tungsten concentrate, the low-grade tungsten concentrate is returned to the tungsten smelting process, and the shaken middlings are returned to the shaking table for further separation; (5) The shaking tailings obtained in step (4) are swept and selected by a blanket concentrator to obtain sweep concentrate and sweep tailings, and the sweep concentrate is returned to step (4) to continue separation and enrichment using a shaking table; (6) The coarse tailings obtained in step (3) and the swept tailings obtained in step (5) are combined, and after adjusting the pH, heavy metal chelating agents and flocculants are added for harmless disposal, and then filtered to obtain industrial solid waste and filter press circulating water. The filter press circulating water is returned to the slurry preparation process for closed-loop circulation after pH adjustment and purification.

2. The method for recovering tungsten from tungsten smelting alkali-boiling slag by gravity separation according to claim 1, characterized in that: Step (1) The mass percentage of WO3 in the tungsten smelting alkali-boiling slag is 0.5-5%, and the mass percentage of WO3 is controlled to change within ±0.5% during the ore blending process, and the mass percentage concentration of the tungsten smelting alkali-boiling slag slurry is adjusted to 10-20%.

3. The method for recovering tungsten from tungsten smelting alkali-boiling slag by gravity separation according to claim 1, characterized in that: The oxidizing dispersant is an inorganic sulfate, and the amount of the dispersant added is 0.5-2‰ of the ore amount. The defoaming agent is a mineral processing defoaming agent, and the amount of addition is 0.5-2kg / t.

4. The method for recovering tungsten from tungsten smelting alkali-boiling slag by gravity separation according to claim 1, characterized in that: Step (2) Wet screening or hydrocyclone pre-classification is performed using a 120-325 mesh screen according to the particle size of the alkali-boiled slag. The mass of the coarse particles is 10-30% of the total slurry mass, and the WO3 grade enrichment ratio in the coarse particles is 1.5-3.

5. The method for recovering tungsten from tungsten smelting alkali-boiling slag by gravity separation according to claim 1, characterized in that: The number of series stages of blanket beneficiation in step (3) and step (5) is 3-10, the mass percentage concentration of the selected slurry is 10-20%, and the WO3 grade enrichment ratio of the concentrate in the roughing and scavenging steps is 1.2-3.

6. The method for recovering tungsten from tungsten smelting alkali-boiling slag by gravity separation according to claim 1, characterized in that: The mass percentage concentration of the slurry entering the shaking table in step (4) is 15-30%, and the grade of the obtained low-grade tungsten concentrate is 10-30%.

7. The method for recovering tungsten from tungsten smelting alkali-boiling slag by gravity separation according to claim 1, characterized in that: Step (6) harmless disposal refers to adding sulfuric acid, nitric acid, oxalic acid or organic acid to the tailings to adjust the pH value to 6-9, and adding heavy metal remover ferrous sulfate and fluorine remover PAC according to the difference in heavy metal pollution and toxicity in the alkali-boiled slag to remove harmful elements such as As, Pb, Cr and F. Depending on the content of arsenic and chromium in the alkali-boiled slag after treatment, an appropriate amount of oxidant ammonium persulfate or hydrogen peroxide is added to react and precipitate to remove the remaining arsenic, and finally PAM is added for two-stage dense flocculation. After harmless disposal, the tungsten slag slurry is filtered to obtain industrial solid waste and filter-pressed circulating water. The filter-pressed circulating water is returned to the system for recycling after sedimentation and standing. When the tungsten in the circulating water reaches a certain concentration, it is recovered by ion exchange and then evaporated.

Images