Dressing and smelting combined method for efficiently recovering tungsten and molybdenum elements from alkaline leaching and autoclaving tungsten slag

Abstract

The invention discloses a dressing and smelting combined method for efficiently recovering tungsten and molybdenum elements from alkaline leaching and autoclaving tungsten slag. The method comprises the following steps: carrying out centrifugal reselection pretreatment on the alkaline leaching and autoclaving tungsten slag; centrifugal gravity concentration concentrate is low-grade tungsten concentrate and can be used as a raw material to be returned to an alkaline leaching and autoclaving process, and gravity concentration tailings and an additive are sufficiently mixed and then roasted; and after the roasted product is ground and screened, water leaching treatment is adopted, and a solution containing tungsten and molybdenum and leaching residues capable of being subjected to building material treatment are obtained. According to the method, the problems that when the tungsten slag is treated through a single wet process, the concentration of acid and alkali liquid is high, waste water treatment and recovery are difficult, and the process is tedious are solved, the low-grade tungsten concentrate is obtained through centrifugal separation by adopting the method of combining gravity separation and pyrometallurgy, and efficient enrichment and separation of tungsten and molybdenum can be achieved by adding a proper additive into gravity separation tailings to conduct roasting and water leaching. The method is low in comprehensive cost and high in extraction efficiency, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to a combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkali leaching and pressing tungsten slag, belonging to the field of comprehensive treatment technology for hazardous waste from smelting. Background Technology

[0002] Tungsten, a rare and precious metal with a high melting point, is widely used in fields such as steel, electrical, medical, and military industries due to its unique properties.

[0003] Among natural minerals, wolframite and scheelite are the main sources of tungsten. Currently, my country's tungsten resources are characterized by a significant decline in wolframite resources, abundant scheelite, numerous associated minerals, a high proportion of low-grade ore, high beneficiation difficulty, and low smelting recovery rates. Furthermore, my country's tungsten smelting process primarily relies on alkaline leaching, inevitably producing alkaline tungsten slag during the process. The tungsten concentrate obtained from beneficiation undergoes a grinding-alkali cooking-ion exchange-evaporation crystallization process to obtain the intermediate product ammonium paratungstate (APT). The solid discharged after extracting metallic tungsten is the alkaline cooking tungsten slag; the production of each ton of APT generates 0.7 to 1.3 tons of tungsten slag. Because the tungsten slag contains valuable elements such as W, Mo, Bi, Fe, and Sn, it possesses significant economic potential.

[0004] Existing research methods for recovering valuable elements from tungsten slag include pyrometallurgical treatment, hydrometallurgical treatment, and flotation. Pyrometallurgical treatment mainly involves placing the target metal element under high-temperature conditions, using a reducing agent to generate an alloy or recover it through volatilization in the flue gas. Its main drawbacks are high energy consumption, environmental pollution, limitations in raw material adaptability, huge investment, and difficulty in controlling impurities. Hydrometallurgical treatment can be divided into acid leaching, alkali leaching, and alkali roasting. Acid leaching is generally lengthy and requires a large amount of acid, while alkali leaching leaves secondary alkaline residues and alkaline solutions, which are difficult to further process. Compared with the previous two metallurgical treatment methods, flotation for recovering valuable elements from tungsten slag has problems such as a high proportion of fine particles and a high specific surface area in the tungsten slag, leading to increased flotation reagent consumption and unsatisfactory recovery results. In conclusion, the comprehensive utilization of tungsten slag and its harmless and resource-based treatment is a key issue facing the tungsten industry, and there is an urgent need to develop new low-cost and efficient recovery methods. Summary of the Invention

[0005] To address the problems of high reagent consumption, high energy consumption, lengthy processes, and incomplete treatment in existing technologies for recovering valuable elements from tungsten slag, the present invention aims to provide a combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressure-cooking tungsten slag. This method first pre-treats the alkaline leaching and pressure-cooking tungsten slag using gravity separation, then mixes the gravity separation tailings with additives and roasts them to convert W and Mo into water-soluble substances. Through multiple cycles of water leaching, W and Mo are enriched in the leachate. This invention reduces the energy consumption and reagent costs in tungsten slag recovery.

[0006] To achieve the above-mentioned technical objectives, this invention provides a combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag, mainly comprising the following steps:

[0007] Step 1

[0008] Alkali-leached and pressure-cooked tungsten slag is subjected to gravity separation pretreatment to obtain gravity separation tailings and gravity separation products; the gravity separation tailings contain less than or equal to 0.85 wt.% W and less than or equal to 0.38 wt.% Mo; the gravity separation contains W and Mo; the gravity separation includes centrifugal gravity separation, and during centrifugal gravity separation, the centrifugal concentrator speed is greater than or equal to 20 g, where g is the acceleration due to gravity;

[0009] Step Two

[0010] The gravity separation tailings are dried, and the dried sample is mixed evenly with additives. This mixture is then added to a covered equipment for roasting to convert tungsten and molybdenum into water-soluble substances, yielding the roasted product. The additives contain A and B, where A is a sodium salt or alkali, and B is a silicon-containing inorganic substance. The mass ratio of the dried sample to the additives is 1.75~4.5:1.

[0011] Step 3

[0012] The roasted product obtained in step two is crushed and leached in water to separate and enrich the tungsten and molybdenum elements in the leaching solution.

[0013] In industrial applications, tungsten slag of different particle sizes is prepared into slurries of a specific concentration. After thorough mixing and dispersion, the slurries are uniformly fed into a centrifugal concentrator for centrifugal separation. The centrifugal gravity concentrate is a low-grade tungsten concentrate, and the tailings are even lower-grade gravity tailings. The gravity concentrate is returned to the alkaline leaching and pressure cooking process for tungsten extraction, while the gravity tailings are used as feedstock for subsequent roasting-water leaching.

[0014] As a preferred embodiment, this invention provides a combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressure leaching tungsten slag. The slag mainly comprises calcium-containing minerals such as fluorapatite, calcite, and spodumene (sodium carbonate), with tungsten primarily existing as scheelite and molybdenum primarily existing as molybdenite. The slag particle size is <0.075 mm. The tungsten content is 1.0~1.5 wt.%, and the molybdenum content is 0.4~0.7 wt.%.

[0015] The alkali-leached and pressure-cooked tungsten slag in this invention includes alkali-cooked tungsten slag.

[0016] As a preferred option, the feed concentration of the alkali leaching and boiling tungsten slag slurry in the gravity separation pretreatment stage is 30~40 wt.%; the centrifugal concentrator speed is 25~55 g, preferably 30~50 g. In this invention, g in the centrifuge speed refers to the acceleration due to gravity. For example, 30 g means that the centrifugal force borne by the particles is 30 times their own weight; the backwash water volume is 6.0~7.5 L / min.

[0017] The reselection pretreatment product contains 3.8~6.4 wt.%, preferably 4.5~6 wt.%, and 0.8~1.3 wt.%, preferably 1.0~1.2 wt.%. This invention achieves a significant improvement in the W and Mo content of the reselection product through appropriate reselection pretreatment parameters.

[0018] The W content in the gravity separation tailings is 0.55-0.85 wt.%, preferably 0.7-0.8 wt.%, and the Mo content is 0.25-0.38 wt.%, preferably 0.3-0.35 wt.%.

[0019] In industrial applications, gravity separation tailings are dried, and the dried sample is mixed evenly with additives. This mixture is then placed in a covered container, which is placed in a sintering furnace for roasting. This process converts tungsten and molybdenum into water-soluble substances, yielding the roasted product. The container can be made of one of the following materials: ceramic, corundum, or silicon carbide, and it should be heat-resistant and alkali-resistant.

[0020] As a preferred embodiment, the additives described in step two are prepared at a mass ratio of A:B = 0.3~2.5:1. This invention's additive is an improvement on the reagents used in the traditional scheelite roasting and water leaching method. Traditional scheelite concentrate typically contains around 50% W, and the transformation of tungsten from scheelite to soluble sodium tungstate can be achieved through the traditional soda roasting process (Na2CO3+SiO2). However, this invention involves the resource recovery of alkaline pressure-cooked tungsten slag. The recovery of residual low-grade tungsten and molybdenum metals in the slag is more difficult, and the traditional soda roasting process consumes a large amount of reagents with low recovery efficiency. Therefore, a certain amount of sodium salt is added to the basic alkaline sodium salt and silicon-containing inorganic materials. Because of its lower melting point, it often acts as a flux during roasting, and at high temperatures, it can locally melt on the surface of the tungsten slag particles to create a liquid phase surface, which is beneficial to the reaction of the additives, enhances the roasting reaction activity, and reduces the amount of alkali and inorganic silicon used during roasting.

[0021] As a preferred embodiment, the additive in step two is a solid powder or crystal, composed of two types of inorganic salts (I and II) and a silicon-containing compound in a certain mass ratio; the ratio of inorganic salt I:inorganic salt II:silicon-containing compound is 0.2~1:0.2~1:1, preferably 0.25~1:0.25~1:1, and more preferably 0.25~0.5:0.25~0.5:1; wherein inorganic salt I includes at least one of sodium chloride and sodium sulfate; inorganic salt II includes at least one of sodium carbonate, sodium bicarbonate, and sodium hydroxide; and the silicon-containing compound includes at least one of silicon dioxide, sodium silicate pentahydrate, and sodium silicate nonahydrate; the mass ratio of tungsten slag to additive is 2~4:1, preferably 2.5~4:1. Traditional soda roasting processes consume large amounts of reagents and have low recovery efficiency. Therefore, a certain amount of sodium salt is added to the basic sodium salt and silicon-containing inorganic materials. Because of its low melting point, it can often act as a flux during roasting. At high temperature, it can locally melt on the surface of tungsten slag particles to generate a liquid phase surface, which is conducive to the action of additives, enhances the roasting reaction activity, and can reduce the amount of alkali and inorganic silicon used during roasting.

[0022] Excessive silicon-containing inorganic matter will consume alkaline sodium salts, weakening the efficiency of soluble conversion of tungsten and molybdenum and increasing slag volume; insufficient sodium salts will prevent calcium ions from being fully fixed, resulting in "re-calcification" of tungsten and molybdenum elements during water leaching, thus reducing the recovery rate. Excessive sodium salts or alkalis will lead to waste of reagents, while insufficient sodium salts will reduce the roasting reaction effect.

[0023] To ensure efficient water leaching, the roasted products need to be ground and sieved. This is because after high-temperature roasting, tungsten slag and additives will generate new substances or undergo phase transformations of existing substances, and some low-melting-point components will melt, causing local particles to stick together, affecting the subsequent water leaching effect. Grinding and sieving are both dry operations to prevent the loss of W and Mo by dissolving in water.

[0024] To ensure sufficient contact between water and the calcined product and improve the dissolution efficiency of W and Mo, the particle size of the calcined product after crushing must be less than 0.18 mm. The conditions for water immersion treatment are: liquid-to-solid ratio of 3-7:1, stirring speed of 100-400 rpm, water immersion temperature of 25-75℃, and water immersion time of 3-20 min. Further optimization yields a liquid-to-solid ratio of 3-5:1, stirring speed of 150-300 rpm, water immersion temperature of 25-40℃, and water immersion time of 5-15 min. Even more preferably, the liquid-to-solid ratio is 3:1, stirring speed of 150 rpm, water immersion temperature of 25℃, and water immersion time of 5 min.

[0025] As a preferred embodiment, the calcination temperature is 800~950℃ and the calcination time is 0.5~1.5 h; more preferably, the calcination temperature is 850℃~875℃ and the calcination time is 45 min~1 h.

[0026] In industrial applications, when the concentration of W in the leachate is less than or equal to 20 g / L and / or the concentration of Mo is less than or equal to 10 g / L, the leachate is used as makeup water for the water leaching treatment in step three; finally, a leachate with high W and Mo elements is obtained through preliminary enrichment.

[0027] As a preferred embodiment, the leachate is circulated 4 to 6 times to further enrich and concentrate W and Mo in the leachate. During the water leaching stage, when the liquid-to-solid ratio is less than 3:1, the roasted slag cannot be fully dispersed in the water, resulting in excessively high slurry concentration and difficulty in stirring. Therefore, by repeatedly recycling the leachate, the overall liquid-to-solid ratio during the water leaching stage is further reduced, thereby improving the leaching efficiency and enrichment ratio of valuable metal elements.

[0028] Based on existing methods for recovering valuable elements from tungsten slag, this invention proposes a highly efficient enrichment and extraction process for tungsten and molybdenum by mixing and roasting additives with tungsten slag, followed by gentle water leaching. In this invention, tungsten slag is an alkaline waste residue with low tungsten and molybdenum content discharged from smelters through alkaline hydrometallurgical processes, which suffers from high treatment costs and difficulties in recycling.

[0029] The sodium salt in the additive of this invention can undergo partial melting during calcination, which is more conducive to its calcination reaction with tungsten slag, and at the same time, it can convert insoluble CaWO4 into soluble Na2WO4. The addition of Si element can help fix Ca element to prevent Na2WO4 from converting back to CaWO4 during the water immersion stage and causing anti-calcification. Under air atmosphere, MoS2 in tungsten slag is fully oxidized to MoO4 after calcination. 2- It can combine with added sodium salt to form soluble Na2MoO4, which can then be extracted by water leaching.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) The combined beneficiation and smelting method of gravity separation pretreatment and gravity separation tailings roasting-water leaching is adopted for tungsten smelting slag, so that some valuable metals such as W and Mo are pre-enriched and separated into a portion of low-grade tungsten concentrate, which can be returned to the metallurgical extraction process, while reducing the amount of slag and processing costs in subsequent treatment.

[0032] (2) The advantage of water leaching is that it uses water as a cheap, environmentally friendly, mild and effective medium to achieve the separation, extraction and dissolution of substances. This invention uses water to leach tungsten smelting slag, and no reaction consumption of leachate is generated in this process; at the same time, the recycling of leachate can enrich W and Mo multiple times, which is convenient for continued extraction in subsequent solutions.

[0033] (3) After leaching the tungsten smelting slag, the main body of the leached slag is CaSiO3, which can be used as an additive for building materials, which is conducive to realizing the secondary resource utilization of waste slag and improving the economic and environmental benefits of the treatment process. Attached Figure Description

[0034] Appendix Figure 1 This is a schematic diagram of the combined beneficiation and smelting process for the efficient recovery of tungsten and molybdenum from alkali leaching and pressure cooking tungsten slag according to the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be described more clearly below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. For those skilled in the art, all other drawings and embodiments obtained based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0036] In the embodiments and comparative examples of this invention, the liquid-to-solid ratio is a mass ratio.

[0037] Example 1

[0038] For alkaline leaching and pressure cooking tungsten slag (particle size <0.075mm) from a tungsten smelter, a gravity separation pretreatment was first performed. The alkaline leaching and pressure cooking tungsten slag was slurryed to prepare a 30wt% tungsten slag slurry. After thorough stirring and dispersion, it was uniformly fed into a centrifugal concentrator for centrifugal separation. The centrifugal concentrator speed was 40 g; the backflushing water flow rate was 7.5 L / min. A concentrate product with higher W and Mo content and a tailings product with lower W and Mo content (W content ≤0.85wt.%, Mo content ≤0.38wt.%) were obtained. The gravity separation tailings product was dried, and the dried sample was mixed evenly with an additive. The additive consisted of a reagent with a mass ratio of sodium chloride:sodium carbonate:silica = 0.25:0.25:1, and the mass ratio of tungsten slag to additive was 3:1. The mixture was then added to a covered crucible, which was placed in a muffle furnace for roasting at 850 ℃ for 1 h. The obtained roasted product was dry-ground and sieved, and the undersize product with a particle size of less than 0.075 mm was collected for subsequent water leaching treatment.

[0039] The screened product was added to experimental water and leached with W and Mo at a liquid-to-solid ratio of 3:1, a stirring speed of 150 rpm, a leaching temperature of 25℃, and a leaching stirring time of 5 min. After leaching, solid-liquid separation was performed to obtain a W and Mo-containing solution and ordinary solid waste product. The W and Mo-containing leachate was recycled 6 times to obtain a preliminarily enriched W and Mo solution. Through the above process, the W grade in the centrifugal gravity separation concentrate of tungsten slag was 5.34%, and the Mo grade was 1.16%, accounting for 45.22% and 29.46% of the recovery rates of W and Mo in the raw tungsten slag, respectively. The leaching rates of W and Mo in the centrifugal tailings of tungsten slag reached 92.37% for W and 94.75% for Mo. In the preliminarily enriched W and Mo solution, the W concentration was 19.57 g / L and the Mo concentration was 8.87 g / L.

[0040] Example 2

[0041] The difference from Example 1 is that the centrifugal separator rotates at a speed of 50 g during centrifugal separation, while other experimental parameters and steps remain the same as in Example 1.

[0042] The W grade in the centrifugal gravity separation concentrate of tungsten slag was 4.87%, and the Mo grade was 1.05%, accounting for 53.88% and 36.88% of the recovery rates of W and Mo in the raw tungsten slag, respectively.

[0043] The leaching rates of W and Mo in the centrifuged tailings of tungsten slag can reach 92.35% for W and 94.66% for Mo. In the preliminarily enriched W and Mo solution, the concentration of W is 19.08 g / L and the concentration of Mo is 8.61 g / L.

[0044] Example 3

[0045] The difference from Example 1 is that the centrifugal separator rotates at a speed of 30 g during centrifugal separation, while other experimental parameters and steps remain the same as in Example 1.

[0046] The W grade in the centrifugal gravity separation concentrate of tungsten slag was 5.87%, and the Mo grade was 1.20%, accounting for 41.43% and 27.11% of the recovery rates of W and Mo in the raw tungsten slag, respectively.

[0047] The leaching rates of W and Mo in the centrifuged tailings of tungsten slag can reach 92.20% for W and 94.38% for Mo. In the preliminarily enriched W and Mo solution, the concentration of W is 19.89 g / L and the concentration of Mo is 8.88 g / L.

[0048] Example 4

[0049] The difference from Example 1 is that the backwash water volume during centrifugation is 6.5 L / min, while other experimental parameters and steps remain the same as in Example 1.

[0050] The W grade in the centrifugal gravity separation concentrate of tungsten slag was 5.13%, and the Mo grade was 1.12%, accounting for 48.32% and 33.02% of the recovery rates of W and Mo in the raw tungsten slag, respectively.

[0051] The leaching rates of W and Mo in the centrifuged tailings of tungsten slag can reach 92.03% for W and 94.30% for Mo. In the preliminarily enriched W and Mo solution, the concentration of W is 19.33 g / L and the concentration of Mo is 8.32 g / L.

[0052] Example 5

[0053] The difference from Example 1 is that the additive is composed of a reagent with a mass ratio of sodium sulfate: sodium bicarbonate: sodium silicate nonahydrate = 0.25: 0.25: 1, while other experimental parameters and steps are consistent with Example 1.

[0054] The W grade in the centrifugal gravity separation concentrate of tungsten slag was 5.31%, and the Mo grade was 1.17%, accounting for 45.32% and 29.86% of the recovery rates of W and Mo in the raw tungsten slag, respectively.

[0055] The leaching rates of W and Mo in the centrifuged tailings of tungsten slag can reach 92.31% for W and 94.70% for Mo. In the preliminarily enriched W and Mo solution, the concentration of W is 19.78 g / L and the concentration of Mo is 8.97 g / L.

[0056] Example 6

[0057] The difference from Example 1 is that the additive consists of a reagent with a mass ratio of sodium chloride:sodium hydroxide:silicon dioxide = 0.25:0.25:1, while other experimental parameters and procedures remain consistent with Example 1. The W grade in the centrifugal gravity separation concentrate of tungsten slag was 5.25%, and the Mo grade was 1.16%, representing W and Mo recoveries of 45.51% and 29.26% respectively from the raw tungsten slag.

[0058] The leaching rates of W and Mo in the centrifuged tailings of tungsten slag can reach 92.76% for W and 94.95% for Mo. In the preliminarily enriched W and Mo solution, the concentration of W is 19.73 g / L and the concentration of Mo is 8.90 g / L.

[0059] Example 7

[0060] The difference from Example 1 is that the additive is composed of a reagent with a mass ratio of sodium chloride:sodium carbonate:silica (silica particle size 0.038mm~0.15mm) = 0.25:0.5:1, and the mass ratio of tungsten slag to additive is 2.5:1. Other experimental parameters and procedures remain consistent with Example 1. The W grade in the centrifugal gravity separation concentrate of the tungsten slag is 5.33%, and the Mo grade is 1.15%, representing W and Mo recovery rates of 45.19% and 29.94% respectively in the raw tungsten slag.

[0061] The leaching rates of W and Mo in the centrifuged tailings of tungsten slag can reach 92.01% for W and 94.46% for Mo. In the preliminarily enriched W and Mo solution, the concentration of W is 19.61 g / L and the concentration of Mo is 8.89 g / L.

[0062] Example 8

[0063] The difference from Example 1 is that the additive is composed of a reagent with a mass ratio of sodium chloride:sodium carbonate:silicon dioxide = 1:1:3, and the mass ratio of tungsten slag to additive is 4:1. Other experimental parameters and steps are consistent with those of Example 1.

[0064] The W grade in the centrifugal gravity separation concentrate of tungsten slag was 5.34%, and the Mo grade was 1.17%, accounting for 45.19% and 29.33% of the recovery rates of W and Mo in the raw tungsten slag, respectively.

[0065] The leaching rates of W and Mo in the centrifuged tailings of tungsten slag can reach 92.58% for W and 95.26% for Mo. In the preliminarily enriched W and Mo solution, the concentration of W is 19.93 g / L and the concentration of Mo is 9.11 g / L.

[0066] Example 9

[0067] The difference from Example 1 is that during the stirring leaching, the stirring speed was 300 rpm, the leaching temperature was 25°C, and the leaching stirring time was 15 min. Other experimental parameters and steps were the same as in Example 1.

[0068] The W grade in the centrifugal gravity separation concentrate of tungsten slag was 5.30%, and the Mo grade was 1.18%, accounting for 44.72% and 29.03% of the recovery rates of W and Mo in the raw tungsten slag, respectively.

[0069] The leaching rates of W and Mo in the centrifuged tailings of tungsten slag can reach 92.24% for W and 94.10% for Mo. In the preliminarily enriched W and Mo solution, the concentration of W is 19.77 g / L and the concentration of Mo is 8.91 g / L.

[0070] Comparative Example 1

[0071] Other conditions are the same as in Example 1, except that the centrifuge speed is 15 g and the backwash water volume is 5 L / min during centrifugation. Other experimental parameters and steps are the same as in Example 1.

[0072] The W grade in the centrifugal gravity separation concentrate of tungsten slag was 1.74%, and the Mo grade was 0.51%, accounting for 92.62% and 74.79% of the recovery rates of W and Mo in the raw tungsten slag, respectively.

[0073] The leaching rates of W and Mo in the centrifuged tailings of tungsten slag can reach 89.75% for W and 93.87% for Mo. In the preliminarily enriched W and Mo solution, the concentration of W is 14.27 g / L and the concentration of Mo is 7.03 g / L.

[0074] Comparative Example 2

[0075] Other conditions were the same as in Example 1, except that the dried sample and additive were mixed evenly. The additive consisted of a reagent with a mass ratio of sodium chloride:sodium carbonate:silica (silica particle size 0.038mm~0.15mm) = 2:2:1. Other experimental parameters and procedures were consistent with Example 1. Ultimately, the leaching rates of W and Mo in the tungsten slag reached 74.01% for W and 77.76% for Mo. In the initially enriched W and Mo solution, the concentration of W was 15.35 g / L and the concentration of Mo was 7.05 g / L.

[0076] Comparative Example 3

[0077] Other conditions were the same as in Example 1, except that the dried sample and additive were mixed evenly. The additive consisted of a reagent with a mass ratio of sodium chloride to sodium carbonate of 1:1, and the mass ratio of tungsten slag to additive was 3:1. Other experimental parameters and procedures were consistent with Example 1. Ultimately, the leaching rates of W and Mo in the tungsten slag reached 36.38% for W and 54.20% for Mo. In the initially enriched W and Mo solution, the concentration of W was 7.21 g / L and the concentration of Mo was 2.66 g / L.

[0078] Comparative Example 4

[0079] Other conditions were the same as in Example 1, except that the dried sample and additive were mixed evenly. The additive consisted of a reagent with a mass ratio of sodium carbonate to silicon dioxide of 0.25:1, and the mass ratio of tungsten slag to additive was 3:1. Other experimental parameters and procedures were consistent with Example 1. Ultimately, the leaching rates of W and Mo in the tungsten slag reached 63.56% for W and 82.53% for Mo. In the initially enriched W and Mo solution, the concentration of W was 13.37 g / L and the concentration of Mo was 7.64 g / L.

[0080] Comparative Example 5

[0081] Other conditions were the same as in Example 1, except that the dried sample and additive were mixed evenly. The additive consisted of a reagent with a mass ratio of sodium chloride to silicon dioxide of 0.25:1, and the mass ratio of tungsten slag to additive was 3:1. Other experimental parameters and procedures were consistent with Example 1. Ultimately, the leaching rates of W and Mo in the tungsten slag reached 16.33% for W and 30.08% for Mo. In the initially enriched W and Mo solution, the concentration of W was 3.68 g / L and the concentration of Mo was 2.88 g / L.

[0082] Comparative Example 6

[0083] Other conditions were the same as in Example 1, except that the mass ratio of tungsten slag to additives was 5:1, and other experimental parameters and procedures remained consistent with Example 1. Ultimately, the leaching rates of W and Mo in the tungsten slag reached 79.63% for W and 74.41% for Mo. In the initially enriched W and Mo solution, the concentrations of W and Mo were 16.52 g / L and 6.75 g / L, respectively.

[0084] Comparative Example 7

[0085] Other conditions were the same as in Example 1, except that the calcination temperature was set to 750 °C and the calcination time to 0.5 h. Other experimental parameters and procedures remained consistent with Example 1. Ultimately, the leaching rates of W and Mo in the tungsten slag reached 57.13% for W and 48.70% for Mo. In the initially enriched W and Mo solution, the concentrations of W and Mo were 11.85 g / L and 4.42 g / L, respectively.

[0086] Comparative Example 8

[0087] Other conditions were the same as in Example 1, except that the calcined product was dry-crushed without grinding or grading, and the undersize product with a particle size smaller than 0.18 mm was not collected before direct water leaching. Other experimental parameters and steps remained consistent with Example 1. Ultimately, the leaching rates of W and Mo in the tungsten slag reached 46.53% for W and 35.84% for Mo. In the initially enriched W and Mo solution, the concentration of W was 9.65 g / L and the concentration of Mo was 3.25 g / L.

[0088] Comparative Example 9

[0089] Other conditions were the same as in Example 1, except that the stirring speed was 50 rpm during stirring leaching, while other experimental parameters and steps remained consistent with Example 1. Ultimately, the leaching rates of W and Mo in the tungsten slag reached 69.03% for W and 61.56% for Mo. In the initially enriched W and Mo solution, the concentrations of W and Mo were 14.32 g / L and 5.59 g / L, respectively.

[0090] Comparative Example 10

[0091] Other conditions were the same as in Example 1, except that no reselection pretreatment was performed; calcination leaching was carried out directly. Other experimental parameters and steps remained consistent with Example 1. Ultimately, the leaching rates of W and Mo in the tungsten slag reached 84.22% for W and 82.11% for Mo. In the initially enriched W and Mo solution, the concentrations of W and Mo were 21.84 g / L and 8.52 g / L, respectively.

[0092] The above descriptions are merely preferred embodiments of the present invention and some examples from the technical exploration process of the present invention. However, the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag, characterized in that, Includes the following steps: Step 1 Alkali-leached and pressure-cooked tungsten slag is subjected to gravity separation pretreatment to obtain gravity separation tailings and gravity separation products; the gravity separation tailings contain less than or equal to 0.85 wt.% W and less than or equal to 0.38 wt.% Mo; the gravity separation contains W and Mo; the gravity separation includes centrifugal gravity separation, and during centrifugal gravity separation, the centrifugal concentrator speed is greater than or equal to 20 g, where g is the acceleration due to gravity; Step Two The gravity separation tailings are dried, and the dried sample is mixed evenly with the additives. Then, the mixture is added to a covered equipment for roasting to convert tungsten and molybdenum into water-soluble substances, thus obtaining the roasted product. The additives contain A and B, where A is a sodium salt or alkali and B is a silicon-containing inorganic substance. The mass ratio of the dried sample to the additives is 1.75~4.5:

1. Step 3 The roasted product obtained in step two is crushed and leached in water to separate and enrich the tungsten and molybdenum elements in the leaching solution.

2. The combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag according to claim 1, characterized in that: The alkaline leaching and pressing tungsten slag has a particle size of <0.075mm, a tungsten content of 1.0~1.5wt.%, and a molybdenum content of 0.4~0.7wt.%.

3. The combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag according to claim 1, characterized in that: The feed concentration of the alkali leaching and boiling tungsten slag slurry in the gravity separation pretreatment stage is 30~40 wt.%; the centrifugal concentrator speed is 30~50 g, and the backwash water flow rate is 6.0~7.5 L / min.

4. The combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag according to claim 1, characterized in that, The reselection pretreatment product contained 3.8–6.4 wt.% W and 0.8–1.3 wt.% Mo. The W content in the gravity separation tailings is 0.55-0.85 wt.%, and the Mo content is 0.25-0.38 wt.%.

5. The combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag according to claim 1, characterized in that: In step two, the additives are prepared in a mass ratio of A:B = 0.3~2.5:

1.

6. The combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag according to claim 1, characterized in that, The additive mentioned in step two is a solid powder or crystal, which is a mixture of two types of inorganic salts (I and II) and a silicon-containing compound in a certain mass ratio; the ratio of inorganic salt I: inorganic salt II: silicon-containing compound is 0.2~1:0.2~1:1, preferably 0.25~1:0.25~1:1, and more preferably 0.25~0.5:0.25~0.5:1; wherein inorganic salt I includes at least one of sodium chloride and sodium sulfate; inorganic salt II includes at least one of sodium carbonate, sodium bicarbonate, and sodium hydroxide; the silicon-containing compound includes at least one of silicon dioxide, sodium silicate pentahydrate, and sodium silicate nonahydrate; the mass ratio of tungsten slag to additive is 2~4:1, preferably 2.5~4:

1.

7. The combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag according to claim 1, characterized in that, The calcined product, after being crushed, has a particle size of less than 0.18 mm. The conditions for the water immersion treatment are: a liquid-to-solid ratio of 3~7:1, a stirring speed of 100~400 rpm, a water immersion temperature of 25~75℃, and a water immersion time of 3~20 min; further optimized to a liquid-to-solid ratio of 3~5:1, a stirring speed of 150~300 rpm, a water immersion temperature of 25~40℃, and a water immersion time of 5~15 min. Even more preferably, the liquid-to-solid ratio is 3:1, the stirring speed is 150 rpm, the water immersion temperature is 25℃, and the water immersion time is 5 min.

8. The combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag according to claim 1, characterized in that, The calcination temperature is 800~950℃ and the calcination time is 0.5~1.5 h; more preferably, the calcination temperature is 850℃~875℃ and the calcination time is 45 min~1 h.

9. The combined beneficiation and smelting method for efficiently recovering tungsten and molybdenum from alkaline leaching and pressing tungsten slag according to claim 1, characterized in that, When the concentration of W in the leachate is less than or equal to 20 g / L and / or the concentration of Mo is less than or equal to 10 g / L, the leachate is used as makeup water for the water leaching treatment in step three. The leachate is circulated 4 to 6 times.

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