CN102815728A - Method for preparing nano-sized magnesium hydroxide and nano-silica by utilization of boron mud - Google Patents

Abstract

The invention relates to a method for preparing nano magnesium hydroxide and nano white carbon black by utilizing boron mud. Add concentrated sulfuric acid to the calcined boron mud for acid leaching and dissociation; the acid leaching solution after acid leaching and dissociation is subjected to solid-liquid separation; The filtrate after ironing is added with particle surface modifier and lye to prepare nano-magnesium hydroxide; the acid leaching residue after solid-liquid separation is used for alkali dissolution and then filtered, and the filtrate is added with particle barrier and acid solution to prepare nano-silica. The technology of the invention can not only efficiently and comprehensively utilize the main components magnesia and silicon dioxide in the boron mud to prepare high value-added products, but also can solve the problem of boron mud polluting the environment. The magnesium hydroxide prepared by the invention is flaky nano-level magnesium hydroxide; the white carbon black is spherical nano-level white carbon black.

Description

A kind of method utilizing boron mud to prepare nano magnesium hydroxide and nano white carbon black

technical field

The invention relates to a method for preparing nano magnesium hydroxide and nano white carbon black by utilizing boron mud, and belongs to the technical field of mineral processing and solid waste utilization.

Background technique

Boron mud is the waste residue produced in the production of boric acid, borax and other products. Boron mud is light red, fine and loose, its main components are MgO and SiO ₂ , and contains a small amount of Fe ₂ O ₃ , Al ₂ O ₃ , CaO, B ₂ O ₃ , etc. Since the boron mud is alkaline, its lye can dissolve into the groundwater, reducing the yield of the surrounding farmland, and in severe cases, it can lead to the failure of the crops and pollute the surrounding drinking water. Therefore, it not only occupies the land, but also causes serious pollution to the surrounding cultivated land, and the land where it is discharged is exhausted and no grass grows. With the continuous development of social economy, the demand for borax and boric acid is increasing year by year, and the output of boron mud will also increase year by year. The treatment of a large amount of boron sludge has become one of the problems to be solved urgently in the development of boron resources and boron ore processing industry.

Boron mud contains valuable elements such as magnesium and silicon, and has high utilization value. Therefore, the development of this secondary resource and the production of high-quality magnesium hydroxide and white carbon black are of great significance to reducing environmental pollution, promoting resource regeneration and improving economic benefits of enterprises.

Aiming at the current environmental pollution caused by boron mud and the current situation of comprehensive utilization, the present invention proposes a method for efficiently utilizing magnesium oxide and silicon dioxide components in boron mud to prepare nano magnesium hydroxide and nano white carbon black.

Contents of the invention

Carry out leaching reaction of boron mud and sulfuric acid solution; filter and wash the reacted slurry to separate solid-liquid components; add appropriate oxidant to the obtained filtrate to oxidize Fe ²⁺ in it, and then add alkali solution to precipitate iron components in the filtrate After filtering to remove precipitates such as ferric hydroxide, add alkali to react, and add an appropriate amount of particle surface modifier; after the reaction, carry out aging, filtering, washing, drying and depolymerization of the reaction system to obtain the original particle size of nano-scale, particle Magnesium hydroxide powder in the shape of flakes; the residue after the reaction of boron mud and sulfuric acid is hydrothermally reacted with sodium hydroxide under heating, the product is filtered after the reaction, and the filtrate is adjusted to a certain concentration by adding water. A certain amount of particle barrier agent is precipitated with acid; the precipitated product is aged, filtered, washed and dried to obtain spherical nano-scale white carbon black.

The process steps and principles are as follows:

(1) Calcining boron mud at a calcination temperature of 300-700°C for 0.5-1.5 hours;

(2) adding water and sulfuric acid to the calcined boron mud to react to obtain a mixed slurry containing magnesium sulfate, aluminum sulfate, ferrous sulfate and ferric sulfate, the reaction formula is:

MgO _{+ H2SO4} → _MgSO4 + _H2O

Al ₂ O ₃ +3H ₂ SO ₄ →Al ₂ (SO ₄ ) ₃ +3H ₂ O

Fe ₂ O ₃ +3H ₂ SO ₄ →2Fe ₂ (SO ₄ ) ₃ +3H ₂ O

FeO _{+ H2SO4} → _FeSO4 + _H2O

(3) Filter the above-mentioned mixed slurry to remove solid residues and adjust to a suitable concentration, add hydrogen peroxide to oxidize ferrous ions for 15-45 minutes, then add alkali to react until the pH value of the slurry is 4-7, and the reaction formula is as follows:

H ₂ O ₂ +2FeSO ₄ +H ₂ SO ₄ ＝Fe ₂ (SO ₄ ) ₃ +2H ₂ O

Fe ₂ (SO ₄ ) ₃ +6NaOH＝2Fe(OH) _3↓ +3Na ₂ SO ₄

(4) After filtering the above-mentioned oxidation reaction product to remove iron hydroxide precipitate, add a particle surface modifier, add alkali to react until the pH value of the slurry is 10-13, and obtain magnesium hydroxide precipitate. Its reaction formula is as follows:

MgSO ₄ +2NaOH＝Mg(OH) _2↓ +Na ₂ SO ₄

(5) Aging, filtering, washing, drying, and depolymerizing the slurry containing magnesium hydroxide precipitate to obtain flaky nano-scale magnesium hydroxide product.

(6) the solid residue filtered out in step (2) is reacted with caustic soda under heating conditions to generate a slurry containing sodium silicate, and its reaction formula is:

SiO ₂ ·nH ₂ O+2NaOH＝Na ₂ O·mSiO ₂ +(n+1)H ₂ O

(7) Filter the above-mentioned slurry containing sodium silicate, remove the solid residue and add water to adjust the Baume degree of the solution to 10-30°, and add acid to precipitate at 30-90°C until the pH value of the slurry is 3-7, and at the same time Add particle barrier agent under stirring to obtain hydrated silica precipitate, the reaction formula is as follows:

Na ₂ O·mSiO ₂ +H ₂ SO ₄ +nH ₂ O→mSiO ₂ ·nH ₂ O _↓ +Na ₂ SO ₄

The reaction product is aged, filtered, washed, dried and depolymerized to obtain a spherical nano-scale white carbon black product.

The boron mud described in the step (1) has a particle size of 50-500 mesh.

The particle surface modifier described in step (4) is one of titanate, silane, aluminate coupling agent, organosilicon or a combination thereof.

The particle barrier agent described in step (7) is one of polyethylene glycol, aluminate coupling agent, titanate coupling agent, silane coupling agent, organosilicon, OP-10 or a combination between them .

Following is formula and process condition of the present invention:

(1) acid soluble: calcined boron mud: 96% sulfuric acid: water (mass ratio)=100: 80～160: 120～240, reaction temperature 90～120 ℃, reaction time 0.5～3h;

(2) Iron removal by oxidation: the amount of 30% H ₂ O ₂ is 1% to 10% of the mass of calcined boron sludge, the reaction temperature is 30 to 80°C, and the aging time is 30 to 60 minutes;

(3) Precipitating Mg(OH) ₂ : the reaction temperature is 30-90°C, the aging time is 15-60min; the amount of surface modifier is 0.3%-5% of the mass of magnesium hydroxide;

(4) Acid soluble slag alkali soluble: acid soluble slag: NaOH: water=100: 20～80: 200～400, reaction temperature 90～120 ℃, reaction time 1～4h;

(5) Precipitation of hydrated silica: the amount of the particle barrier agent is 0.5% to 6% of the mass of nano-silica.

The magnesium hydroxide prepared by the present invention is flaky nano-scale magnesium hydroxide, and has a smaller specific surface area (BET specific surface area is less than ^70m2 /g), relatively high purity (Mg(OH) ₂ content > 98%), Good dispersibility and surface activity; white carbon black products are spherical nano-scale white carbon black products with large specific surface area and pore volume (BET specific surface area greater than 200m ² /g and pore volume greater than 1.0cm ³ /g), high purity ( SiO ₂ content > 98%), light bulk density (bulk density ≤ 0.15g/cm ³ ), good dispersibility and surface activity.

Attached content

Accompanying drawing 1 is the technological process of the present invention, and accompanying drawing 2 is the scanning electron microscope analysis result of flaky nano-scale magnesium hydroxide and spherical nano-scale white carbon black prepared by the embodiment of the present invention.

Detailed ways

Embodiment one:

Calcinate 200g of boron slime at 600°C for 1h; take 100g of calcined boron slime, add 180g of water, 120g of sulfuric acid with a concentration of 96%, react at 95°C for 1.5h; separate the solid and liquid components after filtration; add 5.0g of Hydrogen peroxide with a mass concentration of 30% was reacted at 60°C for 15 minutes; the pH of the system was adjusted by adding sodium hydroxide solution to 6.5, and aged for 30 minutes; after filtering and separating the precipitate, the Baume degree of the solution was adjusted to 20°, Add 0.12g of ethylene glycol, add sodium hydroxide solution dropwise at 80°C until the pH of the system is 13, age for 50 minutes, filter, wash, and dry to obtain a flaky nano-sized magnesium hydroxide product.

Take 40g of dry acid-soluble filter residue, add 120g of water and 13g of solid sodium hydroxide, stir and react at 95°C for 1h, filter to remove the residue, add water to adjust the Baume degree of the filtrate to 20°, add 1.2g of silane, and mix at 70°C Water glass solution with a Baume degree of 20° and a sulfuric acid solution with a mass concentration of 20% were added dropwise to react, and the final pH value of the reaction system was 3.5; after the reaction, it was aged for 50 minutes, and then filtered, washed, dried and depolymerized to obtain a spherical shape. Nanoscale silica products.

Embodiment two:

Calcinate 500kg of boron mud at 600°C for 1h; take 200kg of calcined boron mud, add 360kg of water, 240kg of sulfuric acid with a concentration of 96%, and react at 100±5°C for 1.5h; separate the solid and liquid components after filtration; add 10kg of hydrogen peroxide with a mass concentration of 30% was reacted at 60°C for 15 minutes; the pH value of the system was adjusted by adding sodium hydroxide solution to 6.5, and aged for 30 minutes; Add 0.24 kg of polyethylene glycol, add sodium hydroxide solution dropwise at 80°C until the pH of the system is 13, age for 50 minutes, filter, wash, and dry to obtain a flaky nano-sized magnesium hydroxide product.

Take 80kg of dry acid-soluble filter residue, add 220kg of water and 26kg of solid sodium hydroxide, stir and react at 100±5°C for 1h, filter to remove the residue, add water to adjust the Baume degree of the filtrate to 20°, add 2.4kg of silane, Add sodium silicate solution with a Baume degree of 20° and sulfuric acid with a mass concentration of 20% in a parallel flow to react, and the final pH value of the reaction system is 3.5; after the reaction, age for 50 minutes, then filter, wash, dry and depolymerize That is, a spherical nano-scale white carbon black product is obtained.

Table 1 is the result of detection of physical and chemical properties of the products obtained in the examples.

The detection analysis result of table 1 embodiment sample

Claims (6)

1. method of utilizing boric sludge to be equipped with nano-sized magnesium hydroxide and Nano carbon white is characterized in that its process step is:

(1) boron mud is calcined 1h down at 600 ℃;

(2) will calcine that back boron mud adds water and sulphuric acid soln reacts;

(3) reaction product is filtered separating solid residue;

(4) will filtrate and under 30～80 ℃, add hydrogen peroxide oxidation and alkaline chemical precipitation ironic hydroxide to slurries pH=4～7, and the filtering separation ironic hydroxide;

(5) filtrating after the deironing is added the particle surface modifier, and under 30～90 ℃ of temperature of reaction, add alkali reaction to slurries pH=10～13, after-filtration, washing, drying, depolymerization are accomplished in reaction, nano-sized magnesium hydroxide;

(6) step (3) filter residue hydro-oxidation sodium and water are reacted 1～4h down at 90～120 ℃, and to dope filtration;

(7) will filtrate with sulfuric acid 30～90 ℃ down and stream react to slurries pH=3～7, add the particle barrier agent simultaneously, after-filtration, washing, drying, depolymerization are accomplished in reaction, obtain nano silicon.

2. a kind of method of utilizing boric sludge to be equipped with nano-sized magnesium hydroxide and Nano carbon white according to claim 1; The batching mass ratio that it is characterized in that step (2) is calcining boron mud: 96% sulfuric acid: water (mass ratio)=100: 80～160: 120～240; 90～120 ℃ of temperature of reaction, reaction times 0.5～3h.

3. a kind of method of utilizing boric sludge to be equipped with nano-sized magnesium hydroxide and Nano carbon white according to claim 1 is characterized in that the consumption of ydrogen peroxide 50 is 1%～10% of calcining boron shale amount.

4. a kind of method of utilizing boric sludge to be equipped with nano-sized magnesium hydroxide and Nano carbon white according to claim 1; The particle surface modifier that it is characterized in that step (5) is one of titanic acid ester, silane, aluminate coupling agent, organosilicon or the combination between them, and consumption is 0.3%～5% of a Marinco H quality.

5. a kind of method of utilizing boric sludge to be equipped with nano-sized magnesium hydroxide and Nano carbon white according to claim 1, the batching mass ratio that it is characterized in that step (6) is sour molten slag: NaOH: water=100: 20～80: 200～400.

6. a kind of method of utilizing boric sludge to be equipped with nano-sized magnesium hydroxide and Nano carbon white according to claim 1; The particle barrier agent that it is characterized in that step (7) is one of polyoxyethylene glycol, aluminate coupling agent, titanate coupling agent, silane coupling agent, organosilicon, OP-10 or the combination between them, and consumption is 0.5%～6% of a Nano carbon white quality.

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