CN110396610B - Method for treating titanium minerals and metal silicate minerals through ammonium salt pressure pyrolysis - Google Patents

Abstract

The invention discloses a method for treating titanium minerals and metal silicates by ammonium salt pressure pyrolysis. The method comprises the steps of pretreating titanium minerals and metal silicates, uniformly mixing the pretreated titanium minerals and metal silicates with ammonium salts according to a certain proportion, carrying out low-temperature pyrolysis in a high-pressure kettle, carrying out closed roasting when the pH value of gas at a sampling port is acidic, efficiently salinizing valuable metals in the minerals by utilizing the ammonium salts under a closed condition, releasing valuable elements embedded in lattices, and carrying out acid leaching on roasted slag in dilute acid to obtain a high-concentration acid leaching solution of titanium, aluminum and magnesium; hydrolyzing titanium, aluminum and magnesium in the pickle liquor step by step, and recovering the titanium, aluminum and magnesium in a stepped manner to obtain a high-purity product; meanwhile, the ammonia water is recycled, and the ammonium salt can be recycled through evaporation and crystallization. The method realizes the step recovery of titanium, magnesium, aluminum and ammonium salt in titanium minerals and metal silicates, and realizes the purpose of recycling waste resources.

Description

A kind of method of ammonium salt pressure pyrolysis processing titanium mineral and metal silicate mineral

technical field

The invention belongs to the field of industrial solid waste resource utilization, and relates to a method for extracting titanium, magnesium and aluminum by adopting ammonium salt pressure pyrolysis treatment of titanium minerals and metal silicate minerals.

Background technique

Titanium is very abundant on earth, with a crustal abundance of 0.61%, which is higher than the common copper, nickel, tin, lead, and zinc. There are about 140 kinds of known minerals, but they are basically symbiotic minerals. The main forms of existence are ilmenite, titanomagnetite and hematite. Vanadium-titanium magnetite in Panxi area of China is the world's super-large deposit of polymetallic symbiosis, with reserves of 9.66 billion t, of which titanium (TiO ₂ ) is 873 million t (accounting for 90.5% of the country and 35.17% of the world), and its structure is dense , the gangue content is high, and the crystal grain size is basically about 10 μm. It is difficult to separate the titanium-containing phase by a purely physical beneficiation method. At present, about 53% of the titanium in vanadium titanomagnetite enters the blast furnace smelting process in the form of iron concentrate, and finally forms titanium-containing blast furnace slag. Over the years, most of them are directly stored or used as cement ingredients, which not only wastes resources seriously, occupies a lot of land, but also pollutes the environment. And metal silicate minerals are a class of oxo-acid salt minerals composed of metal cations and silicates. They are the main minerals that constitute the crust and upper mantle. Many silicate minerals have high magnesium and aluminum content, such as high Ridgestone, montmorillonite, zeolite, etc. are important non-metallic mineral raw materials and materials. Most of the valuable metals in metal silicate minerals are present in gangue minerals, with extremely fine particle size and difficult to separate.

At present, the process research of titanium minerals mainly includes direct sulfuric acid leaching method, sub/molten salt method and high temperature carbonitriding-low temperature chlorination method. The direct leaching method of sulfuric acid requires high concentration of sulfuric acid, which will corrode equipment greatly. At the same time, a large amount of acid leaching solution and acid leaching residue will cause secondary pollution; The method for decomposing titanium-containing blast furnace slag in the system does not contain water in the system, but usually the viscosity of the molten reactant is relatively high, and the preparation of the hydrolyzed raw material titanyl sulfate solution is greatly affected by the molten salt reaction and washing. The high-temperature selective reduction carbonitriding-low-temperature chlorination method is processed at a high temperature above 1500 °C, and the energy consumption is huge. For metal silicate minerals, flotation or alkali leaching are mostly used, but metal ions inevitably exist in the mineral flotation system. In addition to activating or inhibiting silicate minerals, metal ions in the solution sometimes Changing the surface electrical properties of minerals affects the dispersion behavior of mineral particles, resulting in extremely unstable flotation; while the alkali solution method has higher costs and more impurity elements in the product.

The patent document "A method for directly producing titanium alloys from titanium-containing minerals" (CN1888101A) discloses a method for directly utilizing titanium-containing minerals to prepare titanium alloys. The high-titanium slag is prepared from iron, and the above-mentioned high-titanium slag is added with electrolytic aluminum in a plasma high-temperature furnace to reduce titanium oxide to obtain a titanium-aluminum alloy mother liquor, and then mixed with 1-10% calcium fluoride and a deoxidizer, and melted in a vacuum electric furnace The titanium-aluminum alloy with an oxygen content of 0.05-0.15% can be obtained. Although the invention realizes metal refining and alloying in metal thermal reduction, and shortens the process cycle, the entire process is carried out in an electric furnace, which is costly. Under the condition, the electrode consumption is serious.

The patent document "Using High Titanium Type Blast Furnace Slag to Prepare Titanium Dioxide" (CN108975393A), discloses a high-temperature carbonization and crushing treatment to obtain carbonized slag; the carbonized slag and chlorine undergo a low-temperature chlorination reaction to obtain a chlorination containing _TiCl4 gas The reaction mixture, the condensed crude TiCl ₄ ; the crude TiCl ₄ is subjected to vanadium removal treatment with fatty acid, and rectified to obtain rectified TiCl ₄ , and the rectified TiCl ₄ is oxidized with O ₂ to obtain an oxidation reaction containing TiO ₂ and Cl ₂ The mixed product is reacted, cooled and filtered to obtain a titanium dioxide product. Although the invention fully recycles the titanium in the high-titanium type blast furnace slag, the high-temperature carbonization temperature is as high as 1580-1700 °C, which requires high equipment and complicated processes.

The patent document "A method for asynchronous conversion of silicate vanadium ore to recover vanadium and silicon" (CN105331816A) discloses a method for recovering silicon and vanadium through two stages of alkali leaching of silicate with low concentration and high concentration. Various silicate minerals such as coal and clay. The method is mainly to finely grind silicate minerals to -200 mesh, accounting for more than 80%, and then leaching through low-concentration alkali solution at high temperature and high pressure, filtering, and collecting the filtrate to prepare water glass with a modulus of ≥ 2; Alkali leaching obtains high-grade concentrate powder, and recovers vanadium by adding 25-40% sulfuric acid. Although this invention adopts high and low concentration two-stage alkali leaching of silicate minerals, which improves the comprehensive utilization rate of resources, but the final vanadium product has many impurity elements and low grade, which can only be used as preliminary enrichment, and at the same time, the consumption of acid and alkali is large, and the cost higher.

To sum up, the current treatment methods for titanium-containing minerals and metal silicate minerals have the disadvantages of low product purity, inability to achieve clean production, and high treatment costs due to their complex structures and serious accompanying phenomena of valuable metals. So far, no one has been found. The technically reasonable and economically feasible method for utilizing titanium-containing blast furnace slag.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is: how to overcome the problems of low leaching rate of titanium, magnesium and aluminum and low product purity in the extraction of titanium minerals and metal silicate minerals, and provide a kind of ammonium salt pressure pyrolysis treatment of titanium minerals and metals Method for silicate minerals.

The invention proposes a method for ammonium salt pressure pyrolysis treatment of titanium minerals and metal silicate minerals, which can efficiently recover titanium, magnesium and aluminum valuable metals, effectively solve the problem of low product purity, obtain high-value products, and The realization of ammonium salt recycling is of great theoretical and practical significance for the efficient utilization of titanium-containing minerals and metal silicates.

A method for ammonium salt pressure pyrolysis treatment of titanium minerals and metal silicate minerals provided by the invention comprises the following steps:

Step 1, drying and dispersing titanium minerals and metal silicate minerals to obtain powder materials;

In step 2, the powder material obtained in step 1 is mixed with ammonium salt, and the roasting device is roasted at 250-450 ° C for 0.5-2 h. The sampling port of the roasting device is opened at the initial stage, the generated ammonia gas is collected, and water is passed into it to form ammonia water. When the pH of the gas at the sampling port is acidic, it is closed and pressurized for pyrolysis;

Step 3, adding the roasting slag obtained by pyrolysis in step 2 to acid leaching with dilute acid solution and filtering;

Step 4. The filtrate obtained in step 3 is kept in a boiling state for 0.5 to 1 h, diluted with water, and then kept in a boiling state for 0.5 to 2 h, and then recrystallized to produce off-white hydrolyzate, and the filtrate and filter residue are collected by filtration. The filter residue is washed with dilute acid to remove impurities and then calcined to obtain titanium dioxide.

According to the method of the present invention, wherein as an option, the method may further include:

Step 5, drop the filtrate obtained in step 4 into the ammonia water formed in step 2 to pH=5～6, and a hydrolysate appears, filter and collect the filtrate and filter residue, wash the filter residue with water to remove impurities and calcine to obtain an alumina product;

Step 6, adding the filtrate obtained in step 5 dropwise to the ammonia water formed in step 2 until pH ≥ 12, a hydrolyzate appears, filtering and collecting the filtrate and the filter residue, washing the filter residue with water to remove impurities and then calcining to obtain a magnesium oxide product;

Step 7, adding the ammonia water formed in step 2 to the filtrate obtained in step 6, and evaporating and crystallizing to obtain ammonium salt crystals.

According to the method of the present invention, as an option, in step 5, after washing the filter residue for 4-8 times to remove impurities, it is calcined at 1000-1300° C. for 1-5 hours;

Step 6: Wash the filter residue for 3 to 6 times to remove impurities, and calcinate at 400 to 800° C. for 2 to 4 hours.

According to the method of the present invention, as an option, in step 1, ball-milling titanium minerals and metal silicate minerals to -0.074mm≥75%, drying and dispersing at 50-110°C to obtain moisture≤2wt % grey powder material.

According to any one of the methods of the present invention, as an option, in step 2, the criterion for controlling the opening and closing of the valve of the sampling port is that the pH of the gas at the sampling port is detected by a pH meter ≤ 7, so as to realize sufficient salinization of valuable elements in the minerals, Forms soluble salts. The roasting device described in step 2 can be any high-pressure roasting device in the art, including but not limited to an autoclave and the like.

According to any one of the methods of the present invention, as an option, in step 2, the powder material is mixed with ammonium salt in a ratio of 1:0.5 to 1:5, wherein the ammonium salt is ammonium sulfate and/or ammonium chloride Ammonium.

According to any one of the methods of the present invention, as an option, in step 3, add H ₂ SO ₄ or HCl solution with a mass fraction of 2% to 30% of the calcined slag at a liquid-solid ratio of 10:1 to 2:1, Acid leaching for 0.5 to 4 hours at 40 to 90° C. and a stirring speed of 100 to 400 rpm.

According to any one of the methods of the present invention, as an option, in step 4, water with a volume fraction of 0.4 to 2 times the volume fraction of the filtrate is added for dilution.

According to any method of the present invention, as an option, in step 4, the filter residue is washed with dilute sulfuric acid or dilute hydrochloric acid with a concentration of 1% to 5% to remove impurities for 6 to 10 times, and calcined at 850 to 1000 ° C to obtain Titanium dioxide.

The titanium minerals and metal silicate minerals of the present invention are mainly perovskite, black titanium, diopside, mayalan garnet and magnesia-aluminum spinel, and the insoluble ammonium salt is pyrolyzed under pressure under airtight conditions. The valuable elements are converted into water-soluble sulfate/chloride salts to achieve the purpose of efficient leaching of valuable elements.

In order to recycle the ammonium salt crystal product more conveniently, as a preference, when ammonium salt is roasted and ammonium sulfate is added, sulfuric acid leaching and washing are preferentially used; when ammonium salt is roasted and ammonium chloride is added, hydrochloric acid acid leaching and washing are preferentially used.

In the present invention, ammonium sulfate and/or ammonium chloride are thermally decomposed to generate SO ₂ , SO ₃ or HCl gas, and the valve of the sampling port can be adjusted to realize full salinization of mineral valuable metals, and at the same time NH ₃ generated by the decomposition returns to participate in the salt reaction, Evaporation and crystallization can realize the recycling of ammonium salt, save cost and be more friendly to the environment.

The beneficial effects of the above-mentioned technical solutions of the present invention are as follows:

(1) By controlling the opening and closing of the sampling port valve, all the SO ₂ , SO ₃ or HCl gas is enclosed in the reactor, so that it is fully salted with titanium, magnesium and aluminum valuable metals to generate soluble sulfate/chloride salt , the leaching rate of titanium magnesium aluminum has been greatly improved, and the resource utilization rate has been effectively improved;

(2) The present invention conducts titanium-magnesium-aluminum cascade recovery for titanium minerals and metal silicate minerals. After ammonium salt roasting and dilute acid leaching, the titanium leaching rate is ≥90%, the aluminum leaching rate is ≥80%, and the magnesium leaching rate is ≥95%. %, adjust the pH value by NH ₃ reuse, and recover the high-value products of titanium, aluminum and magnesium in steps, with obvious economic benefits;

(3) the present invention only needs a low concentration of H ₂ SO ₄ /HCl to leach the titanium, magnesium and aluminum in the roasting product, which effectively reduces the acid consumption;

(4) In the present invention, by controlling the sampling port valve, the ammonia gas is collected, added to the final filtrate, evaporated and crystallized to generate ammonium salt crystals, thereby realizing its recycling, reducing costs, and being environmentally friendly.

Description of drawings

1 is a schematic diagram of the process flow of a method for ammonium salt pressure pyrolysis treatment of titanium minerals and metal silicate minerals according to the present invention.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following descriptions will be given in conjunction with the accompanying drawings and specific embodiments.

As a preferred implementation method of the present invention, the method for treating titanium minerals and metal silicate minerals by pressure pyrolysis of ammonium salts of the present invention comprises the following steps:

Step 1: Ball-grinding titanium minerals and metal silicate minerals to -0.074mm≥75%, drying and dispersing at 50-110°C to obtain gray powder materials with moisture content≤2wt%;

Step 2: Mix the powder material obtained in Step 1 with ammonium salts (ammonium sulfate and/or ammonium chloride) at a ratio of 1:0.5 to 1:5, and roast in an autoclave at 250 to 450°C for 0.5 to 2 hours. Open at the initial stage, collect the generated ammonia gas, pass into distilled water to form ammonia water, when the pH of the gas at the sampling port is acidic, it is closed and pressurized for pyrolysis;

Step 3. Add H ₂ SO ₄ or HCl solution with a mass fraction of 2% to 30% of the calcined slag obtained in step 2 at a liquid-solid ratio of 10:1 to 2:1, and stir at 40 to 90° C. and 100 to 400 rpm. Under the speed, acid leaching for 0.5~4h, filtering, the leaching rate of titanium in the filtrate is ≥96%, the leaching rate of aluminum is ≥92%, and the leaching rate of magnesium is ≥97%;

Step 4. The filtrate obtained in step 3 is kept in a boiling state for 0.5 to 1 h, and 0.4 to 2 times of distilled water is added for dilution, and then the filtrate is kept in a boiling state for 0.5 to 2 h, and recrystallized, and a gray-white hydrolyzate appears, which is collected by filtration. The filtrate and the filter residue are washed with dilute sulfuric acid or dilute hydrochloric acid with a concentration of 1% to 5% to remove impurities for 6-10 times, and calcined at 850 to 1000 ° C to obtain titanium dioxide with a purity of >98%;

Further, the present invention can also continue to carry out the following steps five-seven:

Step 5. Add the filtrate obtained in step 4 dropwise to the ammonia water formed in step 2 to pH=5～6, and a hydrolysate appears, filter and collect the filtrate and filter residue, wash the filter residue with distilled water to remove impurities 4 to 8 times, and heat the residue at 1000～1300 ℃ calcined for 1-5h to obtain alumina products with a purity of >95%;

Step 6. Add the filtrate obtained in step 5 dropwise to the ammonia water formed in step 2 until pH ≥ 12, and a hydrolyzate appears, filter and collect the filtrate and filter residue, wash the filter residue with distilled water to remove impurities 3-6 times, and calcine at 400-800 ° C for 2 ~4h to obtain magnesium oxide product with a purity >97%;

Step 7, adding the ammonia water formed in step 2 to the filtrate obtained in step 6, evaporating and crystallizing to obtain ammonium salt crystals, and realizing recycling.

In the second step, the criterion for controlling the opening and closing of the valve of the sampling port is that the pH of the gas at the sampling port is detected by a pH meter ≤ 7, so as to realize sufficient salinization of the valuable elements in the minerals and generate soluble salts.

Example 1

The chemical composition of the steel slag of Ninggang Group is as follows:

Table 1 Analysis results of steel slag composition

The sample is taken from the steel slag of the oxygen top-blown converter of Ninggang Group. The chemical composition analysis results are shown in Table 1. The main minerals are garnet and cabernet.

Carry out cascade recovery of titanium magnesium aluminum valuable metals according to the method of Fig. 1, concrete steps are as follows:

(1) Roasting with ammonium sulfate

Ball mill the steel slag to -0.074mm to 81.09%, dry at 90°C and disperse, mix the above powder material with ammonium sulfate in a ratio of 1:3, and pyrolyze 1.5% in the autoclave at a temperature of 300°C. h, the sampling port is opened at the initial stage, the generated ammonia gas is collected, and distilled water is introduced to form ammonia water.

(2) Acid leaching

The roasting residue obtained in step (1) was added to the H ₂ SO ₄ solution with a mass fraction of 10% at a liquid-solid ratio of 5:1, and acid leaching was carried out in a water bath with a temperature of 70° C. and a stirring speed of 350 rpm for 3 hours, and the acid leaching was completed. After that, the leaching solution was filtered, and the leaching rates of titanium, magnesium, and aluminum in the acid leaching solution were measured and calculated by ICP to be 97.69%, 94.29%, and 98.45%, respectively.

(3) Recycling of high-value products

The acid leaching filtrate obtained in step (2) was kept in a boiling state for 0.5h, then 1 times of dilution water was added, and the temperature was kept for 1 hour, and recrystallization was carried out, and a gray-white hydrolyzate appeared. Washing and removing impurities 5 times, calcined at 920 ° C, to obtain titanium dioxide with a purity of 98.59%; the ammonia water collected in step (1) was added dropwise to the filtrate to adjust to pH=5.5, and a hydrolyzate appeared, the filtrate and filter residue were collected by filtration, and the filter residue was washed with distilled water to remove Mixed 5 times, calcined at 1100 ° C for 3 hours, to obtain an alumina product with a purity of 96.34%; the above-mentioned filtrate was added dropwise with the ammonia water collected in step (1) to adjust pH=13, and a hydrolyzate appeared, and the filtrate and filter residue were collected by filtration. Washed with distilled water for 5 times to remove impurities, and calcined at 650 ° C for 3 hours to obtain a magnesium oxide product with a purity of 98.57%; the remaining ammonia water was added to the above filtrate, evaporated and crystallized to obtain ammonium sulfate crystals, which were recycled.

Example 2

The chemical composition of the titanium-containing blast furnace slag of Panzhihua Iron and Steel Group is as follows:

Table 2 Composition analysis results of titanium-containing blast furnace slag

The samples were taken from the titanium-containing blast furnace slag after ironmaking in Panzhihua Iron and Steel Group. The chemical composition analysis results are shown in Table 2. The main minerals are perovskite and diopside.

Carry out cascade recovery of titanium magnesium aluminum valuable metals according to the method of Fig. 1, concrete steps are as follows:

(1) Roasting with ammonium sulfate

The titanium-containing blast furnace slag was ball-milled to -0.074mm to 77.28%, dried at 95°C and dispersed, the above powdered material was mixed with ammonium sulfate in a ratio of 1:2, and the temperature was 350°C in the autoclave. Pyrolysis was carried out for 2 hours, the sampling port was opened at the initial stage, the generated ammonia gas was collected, and distilled water was introduced to form ammonia water.

(2) Acid leaching

The roasting slag obtained in step (1) was added to a H ₂ SO ₄ solution with a mass fraction of 8% at a liquid-solid ratio of 8:1, and acid leaching was carried out in a water bath with a temperature of 80° C. and a stirring speed of 390 rpm for 2.5 hours, and the acid leaching was completed. After that, the leaching solution was filtered, and the leaching rates of titanium, magnesium, and aluminum valuable metals in the acid leaching solution were measured and calculated by ICP to be 96.85%, 93.21%, and 97.18%, respectively.

(3) Recycling of high-value products

The acid leaching filtrate obtained in step (2) was kept in a boiling state for 0.7h, then 1.5 times of dilution water was added, and the temperature was kept for 1.2h, and recrystallization was carried out. A gray-white hydrolyzate appeared. The filtrate and the filter residue were collected by filtration, and the filter residue was diluted with 3.5%. Sulfuric acid was washed 5 times to remove impurities, and calcined at 950° C. to obtain titanium dioxide with a purity of 98.81%; the ammonia water collected in step (1) was added dropwise to the filtrate to adjust to pH=5.3, and a hydrolyzate appeared. The filtrate and filter residue were collected by filtration, and the filter residue was washed with distilled water 6 times of impurity removal, calcined at 1250 ° C for 2 hours, to obtain an alumina product with a purity of 97.26%; the above-mentioned filtration was dropwise added with the ammonia water collected in step (1) to adjust pH=12.5, a hydrolyzate appeared, the filtrate and the filter residue were collected by filtration, and the filter residue was Wash with distilled water for 5 times to remove impurities, and calcined at 700 ° C for 2 hours to obtain a magnesium oxide product with a purity of 97.59%; add the remaining ammonia water to the above filtrate, evaporate and crystallize to obtain ammonium sulfate crystals, and realize its recycling.

Example 3

The chemical composition of the high titanium slag of Hegang Co., Ltd. is as follows:

Table 3 Analysis results of high titanium slag composition

The sample was taken from the high titanium slag smelted by the electric furnace of Hegang Co., Ltd. The chemical composition analysis results are shown in Table 3. The main minerals are black titanium stone, silicate glass and free TiO ₂ .

Carry out cascade recovery of titanium magnesium aluminum valuable metals according to the method of Fig. 1, concrete steps are as follows:

(1) Roasting with ammonium sulfate

The high-titanium slag was ball-milled to -0.074mm to be 71.63%, dried at 100°C and dispersed, the above powdered material was mixed with ammonium sulfate in a ratio of 1:4, and the autoclave was heated at a temperature of 400°C. After 2.5 hours of solution, the sampling port was opened at the initial stage, the generated ammonia gas was collected, and distilled water was introduced to form ammonia water.

(2) Acid leaching

Add the calcined slag obtained in step (1) to a H ₂ SO ₄ solution with a mass fraction of 12% at a liquid-solid ratio of 10:1, pickle it in a water bath with a temperature of 85° C. and a stirring speed of 355 rpm for 3.5 hours, and finish the acid leaching. After that, the leaching solution was filtered, and the leaching rates of titanium, magnesium, and aluminum valuable metals in the acid leaching solution were measured and calculated by ICP, which were 97.38%, 94.62%, and 98.57%, respectively.

(3) Recycling of high-value products

The acid leaching filtrate obtained in step (2) was kept in a boiling state for 0.8h, then 0.6 times of dilution water was added, and the temperature was kept for 0.6h, and recrystallization was carried out, and a gray-white hydrolyzate appeared. The filtrate and filter residue were collected by filtration, and the filter residue was diluted with 4% diluted Sulfuric acid was washed 7 times to remove impurities, calcined at 960° C. to obtain titanium dioxide with a purity of 99.34%; the ammonia water collected in step (1) was added dropwise to the filtrate to adjust to pH=5.1, a hydrolyzate appeared, the filtrate and filter residue were collected by filtration, and the filter residue was washed with distilled water 7 times of impurity removal, calcined at 1150 ° C for 1.5 h, to obtain an alumina product with a purity of 96.44%; the ammonia water collected in step (1) was added dropwise to the above filtration to adjust pH=13.2, and a hydrolyzate appeared, and the filtrate and filter residue were collected by filtration. The filter residue was washed with distilled water for 6 times to remove impurities, and calcined at 750°C for 1.5 hours to obtain a magnesium oxide product with a purity of 98.16%; the remaining ammonia water was added to the above filtrate, evaporated and crystallized to obtain ammonium sulfate crystals, which were recycled.

Example 4

The chemical composition of kaolin from a company in Fujian is as follows:

Table 4 Analysis results of kaolin components

The sample was taken from kaolin from a company in Zhangzhou, Fujian. The chemical composition analysis results are shown in Table 4. The main minerals are halloysite and illite.

Carry out cascade recovery of titanium magnesium aluminum valuable metals according to the method of Fig. 1, concrete steps are as follows:

(1) Roasting with ammonium sulfate

The kaolin clay was ball-milled to -0.074mm to be 82.54%, dried at 105°C and dispersed, the above powdered material was mixed with ammonium sulfate in a ratio of 1:3.5, and the temperature was 420°C under the condition of pyrolysis in the autoclave for 2.3 h, the sampling port is opened at the initial stage, the generated ammonia gas is collected, and distilled water is introduced to form ammonia water.

(2) Acid leaching

The roasting slag obtained in step (1) was added to a H ₂ SO ₄ solution with a mass fraction of 7% at a liquid-solid ratio of 12:1, and acid leaching was carried out in a water bath with a temperature of 93° C. and a stirring speed of 410 rpm for 4 hours. After the acid leaching was completed , the leaching solution was filtered, and the leaching rates of titanium, magnesium, and aluminum valuable metals in the acid leaching solution were measured and calculated by ICP to be 98.38%, 95.62%, and 99.17%, respectively.

(3) Recycling of high-value products

The acid leaching filtrate obtained in step (2) was kept in a boiling state for 0.4h, then 1.3 times of dilution water was added, and the temperature was kept for 1.2h, and recrystallization was carried out, and an off-white hydrolyzate appeared. The filtrate and filter residue were collected by filtration, and the filter residue was diluted with 3.5%. Sulfuric acid was washed 6 times to remove impurities, and calcined at 980°C to obtain titanium dioxide with a purity of 98.52%; the ammonia water collected in step (1) was added dropwise to the filtrate to adjust to pH=5.4, and a hydrolyzate appeared. The filtrate and filter residue were collected by filtration, and the filter residue was washed with distilled water 8 times of impurity removal, calcined at 1230 ° C for 1.2 h, to obtain an alumina product with a purity of 97.29%; the ammonia water collected in step (1) was added dropwise to the filtration to adjust pH=13.7, and a hydrolyzate appeared, and the filtrate and the filter residue were collected by filtration. The filter residue was washed with distilled water for 7 times to remove impurities, and calcined at 770 ° C for 1.8 hours to obtain a magnesium oxide product with a purity of 97.96%; the remaining ammonia water was added to the above filtrate, evaporated and crystallized to obtain ammonium sulfate crystals, which were recycled.

Example 5

The chemical composition of the titanium-containing blast furnace slag of Panzhihua Iron and Steel Group is as follows:

Table 5 Composition analysis results of titanium-containing blast furnace slag

The sample was taken from the titanium-containing blast furnace slag after ironmaking in Panzhihua Iron and Steel Group. The chemical composition analysis results are shown in Table 2. The main minerals are perovskite, magnesium-aluminum spinel and titanium-rich diopside.

Carry out cascade recovery of titanium magnesium aluminum valuable metals according to the method of Fig. 1, concrete steps are as follows:

(1) Ammonium chloride roasting

The titanium-containing blast furnace slag was ball-milled to -0.074mm to 83.67%, dried at 110°C and dispersed, the above powdered material was mixed with ammonium chloride in a ratio of 1:0.8, and the autoclave was heated at 310°C. Internal pyrolysis was carried out for 2.5h, the sampling port was opened at the initial stage, the generated ammonia gas was collected, and distilled water was introduced to form ammonia water.

(2) Acid leaching

The roasting slag obtained in step (1) was added to a HCl solution with a mass fraction of 3.5% at a liquid-solid ratio of 6:1, and acid leaching was carried out in a water bath with a temperature of 73° C. and a stirring speed of 375 rpm for 3.6 hours. After the acid leaching, the The leaching solution was filtered, and the leaching rates of titanium, magnesium, and aluminum valuable metals in the acid leaching solution were measured and calculated by ICP, which were 99.27%, 94.92%, and 98.25%, respectively.

(3) Recycling of high-value products

The acid leaching filtrate obtained in step (2) was kept in a boiling state for 0.9h, then 1.3 times of dilution water was added, and the temperature was kept for 1.1h, and recrystallization was carried out, and a gray-white hydrolyzate appeared. The filtrate and filter residue were collected by filtration, and the filter residue was diluted with 2.4%. Washed with hydrochloric acid to remove impurities 6 times, calcined at 960 ° C to obtain titanium dioxide with a purity of 99.12%; the filtrate was adjusted to pH=5.6 by adding the ammonia water collected in step (1), a hydrolyzate appeared, the filtrate and filter residue were collected by filtration, and the filter residue was washed with distilled water 7 times of impurity removal, calcined at 1280° C. for 2 hours to obtain an alumina product with a purity of 98.86%; the above-mentioned filtration was dropwise added with the ammonia water collected in step (1) to adjust pH=12.6, a hydrolyzate appeared, the filtrate and the filter residue were collected by filtration, and the filter residue was Washed with distilled water for 6 times to remove impurities, calcined at 710 ° C for 2 hours to obtain a magnesium oxide product with a purity of 98.47%; the remaining ammonia water was added to the above-mentioned filtrate, evaporated and crystallized to obtain ammonium chloride crystals, which were recycled.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention will not depart from the spirit and scope of the technical solutions of the present invention, and should be included in the present invention. within the scope of the claims.

Claims (8)

1. A method for ammonium salt pressure pyrolysis treatment of titanium minerals and metal silicate minerals, comprising the following steps: Step 1, drying and dispersing titanium minerals and metal silicate minerals to obtain powder materials; In step 2, the powder material obtained in step 1 is mixed with ammonium salt, and the roasting device is roasted at 250-450 ° C for 0.5-2 h. The sampling port of the roasting device is opened at the initial stage, the generated ammonia gas is collected, and water is introduced into it to form ammonia water. When the pH of the gas at the sampling port is acidic, it is closed and pressurized for pyrolysis; Step 3, adding the calcined slag obtained by pyrolysis in step 2 into H ₂ SO ₄ or HCl solution with a mass fraction of 2% to 30% for acid leaching and filtering; Step 4. Keep the filtrate obtained in step 3 at a boiling state for 0.5~1h, add water with a volume fraction of 0.4~2 times the volume fraction of the filtrate to dilute, and then keep it at a boiling state for 0.5~2h, and then recrystallize. Off-white hydrolyzate, filtrate and filter residue were collected by filtration, and the filter residue was washed with dilute acid to remove impurities and then calcined to obtain titanium dioxide. 2. The method according to claim 1, wherein the method further comprises: Step 5, adding the filtrate obtained in step 4 dropwise to the ammonia water formed in step 2 to pH=5～6, a hydrolyzate appears, filtering and collecting the filtrate and the filter residue, washing the filter residue with water to remove impurities and calcining to obtain an alumina product; Step 6, adding the filtrate obtained in step 5 dropwise to the ammonia water formed in step 2 until pH ≥ 12, a hydrolyzate appears, filtering and collecting the filtrate and the filter residue, washing the filter residue with water to remove impurities and then calcining to obtain a magnesium oxide product; Step 7, adding the ammonia water formed in step 2 to the filtrate obtained in step 6, and evaporating and crystallizing to obtain ammonium salt crystals. 3. method according to claim 2, is characterized in that, after step 5, after filtering residue washing and removing impurities 4～8 times, calcining at 1000～1300 ℃ for 1～5h; Step 6: Wash the filter residue for 3 to 6 times to remove impurities, and calcinate at 400 to 800°C for 2 to 4 hours. 4. The method according to any one of claims 1-3, characterized in that, in step 1, titanium minerals and metal silicate minerals are ball-milled to -0.074mm≥75%, dried at 50-110°C and scattered , to obtain a gray powder material with a moisture content of ≤2wt%. 5. The method according to any one of claims 1-3, characterized in that, in step 2, the control criterion for valve opening and closing of the sampling port is to detect the gas pH≤7 of the sampling port by a pH meter, so as to realize sufficient salt of valuable elements in the minerals. to form soluble salts. 6. according to any described method of claim 1-3, it is characterized in that, step 2 mixes powder material and ammonium salt by 1:0.5～1:5 ratio, wherein, described ammonium salt is ammonium sulfate and/ or ammonium chloride. 7. according to the arbitrary described method of claim 1-3, it is characterized in that, in step 3, adding mass fraction of roasting slag by liquid-solid ratio 10:1～2:1 is 2%～30% H ₂ SO ₄ or HCl solution, acid leaching at 40~90℃, 100~400 rpm stirring speed for 0.5~4h. 8. according to the arbitrary described method of claim 1-3, it is characterized in that, step 4 is that 1%～5% dilute acid washing and removing impurities are washed 6～10 times with filter residue with concentration, at 850～1000 ℃ of calcinations, obtain Titanium dioxide.

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