CN104030328A - Method for extracting magnesium oxide and preparing active porous silicon dioxide material by using serpentine - Google Patents

Abstract

The invention discloses a method for extracting magnesium oxide from serpentine to prepare an active porous silica material, comprising the following steps: 1) taking serpentine raw material for pretreatment, and processing it into serpentine mineral powder; The obtained serpentine ore powder is mixed with acid salt, roasted to obtain roasted product and tail gas; 3) the roasted product is post-treated to obtain crude magnesium sulfate solution and active silica residue; 4) the above crude magnesium sulfate solution is and the active silica residue are treated separately; wherein, the crude magnesium sulfate solution is precipitated step by step to obtain a refined magnesium sulfate solution; the active silica residue is dried and pulverized to obtain an active porous silica material. The invention chooses acid salt as an auxiliary agent for removing metal oxides in serpentine, which has high chemical activity, simple process flow, low roasting temperature, short roasting time, low energy consumption and high magnesium oxide leaching rate.

Description

Method for preparing active porous silica material by extracting magnesium oxide from serpentine

technical field

The invention relates to a method for preparing active porous silicon dioxide material by extracting magnesium oxide from serpentine, which belongs to the fields of development and utilization of non-metallic ore, inorganic non-metallic materials, solid waste treatment, mineral processing and environmental protection.

Background technique

Serpentine belongs to the 1:1 type layered silicate, which is composed of silicon-oxygen tetrahedral sheets and magnesium-oxygen octahedral sheets, mainly including chrysotile, antigorite and lizardite. The main mineral composition of serpentinite, serpentine tailings and asbestos tailings is serpentine, containing a small amount of magnetite, talc, brucite, dolomite, calcite, etc. The main chemical composition is SiO ₂ , MgO, containing a small amount of Fe ₂ O ₃ , Al ₂ O ₃ , NiO, Cr ₂ O ₃ , etc. Among them, magnesium oxide is the main metal oxide.

At present, the common method of serpentine resource utilization is to add organic acid and inorganic acid to the serpentine raw material and directly pickle to prepare magnesium-containing compound products. The organic acids used include citric acid, oxalic acid, 2-nitro-4 -Phenylarsonic acid, etc., and inorganic acids include hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, etc. The residue after extracting magnesium oxide from serpentine is directly reacted with sodium hydroxide to prepare chemical products such as sodium metasilicate or white carbon black.

The Chinese patent "Method for Comprehensive Utilization of Asbestos Tailings" with the announcement number 101792184A discloses a method for resource utilization by direct acid leaching. The Chinese patent No. 102352435A "A high-efficiency leaching process of metal ions in chrysotile nanofibers" discloses a multi-stage leaching method using low-concentration hydrochloric acid, sulfuric acid or nitric acid as a leaching agent.

The disadvantages of the above-mentioned disclosed acid leaching methods are that the acid treatment reaction is insufficient, the leaching rate of magnesium oxide is low, and secondary pollution is easily caused during the treatment process; and the acid and alkali solutions are easy to corrode the container, which requires high equipment requirements and high corrosiveness in operation. ,high cost.

For this reason, researchers have developed a method for roasting serpentine with ammonium salt; as the Chinese patent "A Method for Serpentine Processing and Utilization" with the announcement number 102627302A, it discloses a method for roasting serpentine with ammonium salt. Mixed roasting, roasting filtrate and filter residue to prepare silicon and magnesium series compounds. The Chinese patent No. 103496723A "A Method for Improving the Dissolution Rate of Magnesium in Roasted Products of Serpentine Ammonium Salt" also discloses a method of mixing and roasting serpentine mineral powder and ammonium salt to increase the extraction rate of magnesium. The ammonium salt roasting method has more advantages than the acid leaching method; however, the ammonium salt roasting process requires high roasting temperature, small reaction temperature range, weak acidity, long roasting time, large energy consumption, and high requirements for raw material particle size.

So far, no active porous silica materials have been prepared by extracting magnesium oxide from serpentine and acid salts. The technology has little corrosion to equipment, little environmental pollution, low operating and roasting temperatures, and low energy consumption. Public reports of low-cost related technologies.

Contents of the invention

In order to solve the above-mentioned defects in the prior art, the object of the present invention is to provide a method for efficiently extracting magnesia by reacting serpentine and acid salt to prepare active porous silica material.

In order to achieve the above object, the present invention adopts the following technical scheme; a method for extracting magnesium oxide from serpentine to prepare active porous silica material, comprising the following steps:

1) taking serpentine raw materials for pretreatment to obtain serpentine powder; the mass percentage of MgO in the serpentine powder is 30% to 45%;

2) Roasting after mixing the serpentine ore powder obtained in step 1) with the acid salt to obtain roasted products and tail gas; the mixing of the serpentine ore powder and the acid salt refers to the mixture of MgO and the serpentine ore powder in the serpentine ore powder The molar ratio of said acid salt is 1:0.5～1:5;

3) Post-treating the roasted product obtained in step 2) to obtain crude magnesium sulfate solution and active porous silica residue;

4) Reprocessing the active porous silica residue obtained in step 3) to obtain the active porous silica material.

The serpentine raw material used in the above step 1) is at least one of serpentine, serpentine tailings or chrysotile tailings; the particle size of the serpentine ore powder is 60 mesh to 600 mesh.

The acid salt used in the above step 2) can be at least one of ammonium bisulfate, sodium bisulfate, ammonium bisulfite or sodium bisulfite; ~4h; wherein, the roasted product contains sulfate formed by the reaction of serpentine minerals and acid salt; the tail gas is purified by sulfuric acid solution method.

The post-treatment in the above-mentioned step 3) includes leaching, filtering and washing processes; the leaching is adding industrial water to the roasted product to dissolve the sulfate therein, and the solid-to-liquid ratio of the roasted product and industrial water is 1 :5～1:40; described filtering is to adopt filter press to filter, and filtrate is described crude magnesium sulfate solution, and filter residue is active silicon dioxide residue; Described washing is to add filter residue to industrial water, Repeat washing and filtering to make the filter residue neutral to obtain the active porous silica residue.

The reprocessing in the above step 4) is to dry the active porous silica residue after washing and filtering at a drying temperature of 110-700°C, and then grind it to a particle size of 50 mesh to 3250 mesh to obtain the described active porous silica material.

Owing to having adopted above-mentioned technical scheme, the beneficial effect of the present invention is as follows: 1) used chemical auxiliary agent is acid salt in the described preparation method; Because of its low fusing point, when mixed roasting with serpentine raw material, become molten state, completely Ionized and strongly acidic, the metal oxide in the mixture is removed in the presence of a liquid phase, and the metal oxide leaching rate is greater than 96%; the process is simple, the roasting temperature is low, the roasting time is short, the reaction is sufficient, and the energy consumption is low. Low, the leaching time is greatly shortened; it has more advantages compared with the use of ammonium salts and the like as chemical auxiliary agents in the prior art. 2) The raw materials selected in this method are serpentinite, serpentine and asbestos tailings, which provide a new way for its resource utilization; it is beneficial to turn waste into profit, and it also plays a role in the environmental pollution around the above-mentioned mines. Play a positive role, benefit the country and the people. 3) Utilize roasting method of the present invention, the soluble salt that the roasted product that obtains forms, obtains crude magnesium sulfate salt and active porous silica residue through water immersion, washing, filtration; The refined magnesium sulfate solution obtained by precipitation is used to prepare magnesium-containing compounds; the active porous silica residue is added to alkaline raw materials for reaction to prepare silicate materials; or dried and ground to the required particle size to prepare active porous Silica material has large specific surface area, small pore size and uniform distribution. 4) The technological process of the whole preparation process is short, and the amount of chemical additives is small, so the corrosion to mechanical equipment is also small, which can reduce the maintenance input cost of mechanical equipment.

The working principle of the present invention is metal oxide removal, that is, the process of removing metal oxides such as magnesium oxide and retaining active silicon dioxide from the serpentine raw material through chemical reaction. Due to the large difference in electrode potential between metal oxides such as magnesium oxide and silicon dioxide components in the serpentine raw material, metal oxides with more active electrochemical properties dissolve into the electrolyte under the action of the electrolyte and leave electrochemical properties. Stabilized silica residue.

Detailed ways

The present invention prepares the method for active porous silicon dioxide material, comprises steps as follows:

1) taking serpentine raw materials for pretreatment, that is, conventional crushing, grinding and magnetic separation to process serpentine mineral powder; the mass percentage of MgO contained in the serpentine mineral powder is 30% to 45%; Described pretreatment includes conventional crushing, grinding, magnetic separation; Serpentine raw material used can select at least one in serpentine, serpentine tailings or chrysotile tailings; the particle size of serpentine ore powder is 60 mesh to 600 mesh.

2) Mix the serpentine ore powder obtained in step 1) with the acid salt, and roast at a high temperature of 110-800°C for 0.2-4 hours to obtain the roasted product and tail gas; wherein, the serpentine ore powder and the acid salt are mixed The molar ratio of MgO and acid salt in serpentine ore powder is 1:0.5-1:5; the tail gas is purified by sulfuric acid solution absorption method.

3) post-processing the roasted product obtained in step 2) to obtain crude magnesium sulfate solution and active porous silica residue;

4) The crude magnesium sulfate solution obtained in step 3) and the active porous silica residue are reprocessed respectively; wherein, the crude magnesium sulfate solution obtains a refined magnesium sulfate solution through a conventional fractional precipitation method; the active porous silica The silicon residue is dried and ground to obtain an active porous silica material.

The acid salt used in the above step 2) can be selected from at least one of ammonium bisulfate, sodium bisulfate, ammonium bisulfite or sodium bisulfite; the above-mentioned roasted product contains sulfate.

The post-treatment in the above step 3) includes leaching, filtering and washing processes; wherein, leaching is adding industrial water to the roasted product and mixing, and the solid-to-liquid ratio of the roasted product to industrial water is 1:5 to 1:40; Mix and stir to form a sulfate solution; after filtering through a filter press, the above-mentioned crude magnesium sulfate solution and activated silica filter residue are obtained; washing is to add industrial water to the filter residue, and repeat washing to make the filter residue neutral and obtain active Porous silica residue;

The crude magnesium sulfate solution that step 3) obtains obtains refining magnesium sulfate solution through fractional precipitation method; This refining magnesium sulfate solution is used as chemical raw material, prepares the compound containing magnesium series; Active porous silicon dioxide residue is in above-mentioned washing process Finally, it is dried at a temperature of 110-700°C; then, it is ground to obtain an active porous silica material; the grinding particle size is 50 mesh to 3250 mesh.

The sulfuric acid solution absorption method of the above-mentioned step 2) is to purify by reacting the sulfuric acid solution with the ammonia, sulfur trioxide and sulfur dioxide gas in the tail gas.

The step-by-step precipitation method of the above-mentioned step 4) for processing the crude magnesium sulfate solution is specifically to calculate the pH value of the metal ion to start to precipitate according to the solubility product constant of different metal ion precipitation and to carry out the step-by-step precipitation to obtain a variety of nickel, chromium and iron. Metal hydroxide precipitates (nickel hydroxide, chromium hydroxide, iron hydroxide) and refined magnesium sulfate solution.

The magnesium-containing series compounds prepared above include: magnesium hydroxide, magnesium oxide, basic magnesium carbonate, and magnesium carbonate-containing magnesium series compounds.

The technical solutions of the present invention will be further described in detail below in conjunction with specific examples.

Example 1:

This example chooses serpentine as raw material.

1) Crushing, grinding, and magnetically separating the serpentine raw materials to process them into serpentine powder. The particle size is 60 mesh, and the mass percentage of MgO is 45%. The pretreatment includes conventional crushing, grinding and magnetic separation processes.

2) Calculate the mass ratio of the serpentine mineral powder obtained in step 1) based on the molar ratio of MgO and ammonium bisulfite being 1:5, weigh the material and mix and stir evenly; after roasting at 800°C for 0.2h, the obtained Roasting products and tail gas; Among them, sulfur trioxide, sulfur dioxide or ammonia in the tail gas are collected by conventional sulfuric acid solution absorption method.

3) post-treatment the roasted product obtained in step 2); wherein the post-treatment includes leaching, filtering and washing steps; Mix in a device with a stirrer to extract the sulfate in the roasted product; after filtering through a filter press, a crude magnesium sulfate solution and filter residue are obtained; washing is to add industrial water to the filter residue, and repeatedly rinse to make the filter residue reach medium properties to obtain active porous silica residues.

4) The crude magnesium sulfate solution obtained in step 3) and the active porous silica residue are reprocessed respectively; wherein, the crude magnesium sulfate solution obtains refined magnesium sulfate solution through a conventional step-by-step precipitation method; the active porous two The silicon oxide residue is then dried at a drying temperature of 400° C., and then ground to obtain an active porous silicon dioxide material, wherein the grinding particle size is 50 mesh.

The leaching rate of magnesium oxide in this example is 96.3%; Refining magnesium sulfate solution can be used for preparing magnesium series compounds such as magnesium hydroxide, magnesium oxide, basic magnesium carbonate and magnesium carbonate; The obtained active porous silica material The specific surface area is 82.5m ² /g, and the average pore diameter is 1.8nm.

Example 2

This implementation example selects serpentine tailings as raw material; its preparation method is basically the same as Example 1, and will not be repeated here; its difference is:

1) crushing, grinding, and magnetically separating the serpentine tailings to obtain serpentine powder, the particle size of which is 600 mesh, and the mass percentage of MgO in the serpentine powder is 30%;

2) Calculate the mass ratio of the serpentine ore powder obtained in step 1) according to the molar ratio of MgO and ammonium bisulfate as 1:0.5, weigh the material and mix and stir evenly; put it into a temperature-controlled reaction with an exhaust gas collection device In the device, the reaction was roasted at 110° C. for 4 hours; the gas generated during the reaction was collected by conventional sulfuric acid solution absorption method.

3) post-processing the roasted product obtained in step 2); wherein the post-treatment includes leaching, filtering and washing processes; Mix in a device with a stirrer to extract the sulfate in the roasted product; after filtering through a filter press, a crude magnesium sulfate solution and filter residue are obtained; washing is to add industrial water to the filter residue, and repeatedly rinse to make the filter residue reach medium properties to obtain active porous silica residues.

4) The crude magnesium sulfate solution and the active porous silica residue obtained in step 3) are reprocessed respectively. Among them, the crude magnesium sulfate solution is subjected to a conventional fractional precipitation method to obtain a refined magnesium sulfate solution; the active porous silica residue is dried at a drying temperature of 700 ° C, and then pulverized to obtain an active porous silica material, wherein , The grinding particle size is 600 mesh.

In this example, the leaching rate of magnesium oxide is 97.1%; the refined magnesium sulfate solution can prepare magnesium series compounds such as magnesium hydroxide, magnesium oxide, basic magnesium carbonate and magnesium carbonate; the ratio of the obtained active porous silica material The surface area is 156.5m ² /g, and the average pore diameter is 2.6nm.

Example 3

This example chooses chrysotile tailings as raw material. Its preparation method is basically the same as Example 1, and will not repeat them here; its difference is:

1) Crushing, grinding, and magnetically separating the chrysotile tailings to obtain chrysotile tailings ore powder, the particle size of which is 200 mesh, and the mass percentage of MgO is 35%;

2) Calculate the mass ratio of the chrysotile tailings powder obtained in step 1) according to the molar ratio of MgO and sodium bisulfate as 1:3.0, weigh the material and mix and stir evenly; put it into a temperature control system with a tail gas collection device In the reaction device, the reaction was roasted at 380° C. for 2 hours; the tail gas generated during the reaction was collected by conventional sulfuric acid solution absorption method.

3) post-treatment the roasted product obtained in step 2); wherein the post-treatment includes leaching, filtering and washing steps; Mix in a device with a stirrer to extract the sulfate in the roasted product; the filtration is to filter with a filter press to obtain a crude magnesium sulfate solution and filter residue; the washing is to add the filter residue to industrial water , repeated washing to neutralize the filter residue, and obtain active porous silica residue.

4) The crude magnesium sulfate solution obtained in step 3) and the active porous silica residue are reprocessed respectively; wherein, the crude magnesium sulfate solution obtains a refined magnesium sulfate solution through a conventional fractional precipitation method; the active porous silica The silicon residue was dried at a drying temperature of 110° C., and then pulverized to obtain an active porous silica material, wherein the pulverized particle size was 3250 mesh.

The leaching rate of magnesium oxide in this embodiment is 96.9%; The refined magnesium sulfate solution can directly adopt conventional methods to prepare magnesium series compounds such as magnesium hydroxide, magnesium oxide, basic magnesium carbonate; the obtained active porous silica material The specific surface area is 257.8m ² /g, and the average pore diameter is 2.3nm.

Example 4

This example chooses serpentinite and chrysotile tailings as raw materials. Its preparation method is basically the same as Example 1, and will not repeat them here; its difference is:

1) crushing, grinding, and magnetic separation of serpentinite and chrysotile tailings to obtain serpentine ore powder, the particle size of which is 120 mesh, and the mass percentage of MgO is 38.8%;

2) Calculate the mass ratio of the serpentine ore powder obtained in step 1) according to the molar ratio of MgO and sodium bisulfate as 1:4.0, weigh the material and mix and stir evenly; put it into a temperature-controlled reaction with an exhaust gas collection device In the device, the reaction is roasted at 400°C for 1.5 hours; the tail gas generated during the reaction is collected by the conventional sulfuric acid solution absorption method.

3) post-processing the roasted product obtained in step 2); wherein the post-treatment includes leaching, filtering and washing processes; Mix in a device with a stirrer to extract the sulfate in the roasted product; the filtration is to filter with a filter press to obtain a crude magnesium sulfate solution and filter residue; the washing is to add the filter residue to industrial water , repeated washing to neutralize the filter residue, and obtain active porous silica residue.

4) The crude magnesium sulfate solution obtained in step 3) and the active porous silica residue are reprocessed respectively; wherein, the crude magnesium sulfate solution obtains a refined magnesium sulfate solution through a conventional fractional precipitation method; the active porous silica The silicon residue is dried at a drying temperature of 500° C., and then ground to obtain an active porous silica material, wherein the grinding particle size is 1250 mesh.

In this example, the leaching rate of magnesium oxide is 97.6%; the refined magnesium sulfate solution can directly adopt conventional methods to prepare magnesium series compounds such as magnesium hydroxide, magnesium oxide, basic magnesium carbonate; the obtained active porous silica material The specific surface area is 226.5m ² /g, and the average pore diameter is 2.1nm.

Claims (5)

1. A method for preparing active porous silica material by extracting magnesium oxide from serpentine, comprising steps as follows: 1) taking serpentine raw materials for pretreatment to obtain serpentine mineral powder; the mass percentage of MgO in the serpentine mineral powder is 30% to 45%; 2) Roasting after mixing the serpentine ore powder obtained in step 1) with the acid salt to obtain roasted product and tail gas; the mixing of the serpentine ore powder and the acid salt refers to the mixture of MgO and The molar ratio of the acid salt is 1:0.5～1:5; 3) Post-treating the calcined product described in step 2) to obtain crude magnesium sulfate solution and active porous silica residue; 4) Reprocessing the active porous silica residue obtained in step 3) to obtain the active porous silica material. 2. The method according to claim 1, characterized in that: step 1) said serpentine raw material is at least one of serpentine, serpentine tailings or chrysotile tailings; said serpentine ore powder The particle size is 60 mesh to 600 mesh. 3. The method according to claim 2, characterized in that: step 2) said acid salt is at least one of ammonium bisulfate, sodium bisulfate, ammonium bisulfite or sodium bisulfite; The roasting temperature is 110-800° C., and the roasting time is 0.2-4 hours; the roasted product contains sulfate. 4. The method according to any one of claims 1-3, characterized in that: the post-treatment in step 3) includes leaching, filtering and washing processes; the leaching step is to add Industrial water is used to dissolve the sulfate in the roasted product, and the solid-to-liquid ratio of the roasted product to industrial water is 1:5 to 1:40; the filter is filtered by a filter press, and the obtained filtrate is the crude sulfuric acid Magnesium solution, the obtained filter residue is added to industrial water to repeat the washing and filtering steps, so that the pH value of the filter residue is neutral, and the active porous silica residue is obtained. 5. The method according to claim 4, characterized in that: the active porous silica residue obtained in step 4) is dried at a drying temperature of 110-700°C, and then ground to a particle size of 50 mesh to 3250 mesh to obtain the active porous silica material.