The invention discloses a method for crystal seed precipitation of a sodium aluminate solution, comprising the following steps of: 1), mixing a sodium aluminate solution with Al(OH)3 crystal seeds, starting to stir and precipitate at 60 DEG C to 80 DEG C, wherein the causticity ratio of the sodium aluminate solution is 1.25 to 1.60 and the crystal seed coefficient is 1.0 to 4.0; 2), cooling the precipitation system to 40-50 DEG C; and 3), continuously heating the precipitation system within 5 hours to 20 hours, wherein the heating amplitude is 5 DEG C to 25 DEG C, and the final temperature is not higher than 65 DEG C. By adoption of the method provided in the invention, the crystal seed precipitation process of the sodium aluminate solution is effectively reinforced, and the technical and economical indexes of yield in the precipitation, cycle efficiency of aluminium oxide production, and the like are improved.

Method for crystal seed precipitation of sodium aluminate solution

The invention discloses a preparation method of superfine high-white aluminum hydroxide The method includes adding active crystal seeds prepared from industrial-grade aluminium hydroxide into sodium aluminate solution, preparing superfine high-white aluminum hydroxide by means of seed decomposition, and separating, washing and drying the superfine high-white aluminum hydroxide subjected to seed decomposition to obtain the superfine high-white aluminum hydroxide The number of crystal seeds can be reduced effectively, problems caused in the circulation process of the crystal seeds are solved thoroughly, stability of product quality is ensured, and the superfine high-white aluminum hydroxide has competitive advantage comparing with similar products and is simple in technical process, high in operability, less in equipment investment, low in cost, environment friendly and pollution free; meanwhile, materials in the technical process is recyclable, and clean production is realized accordingly

Preparation method of superfine high-white aluminum hydroxide

The present invention addresses the problem of providing a method for producing vanadium dioxide-containing particles having excellent thermochromic performance and transparency. This method for producing vanadium dioxide-containing particles is a method for producing, using hydrothermal reaction, vanadium dioxide-containing particles having thermochromic performance, wherein the method is characterized in that the vanadium dioxide-containing particle surface is surface modified without causing separation of a solvent and the vanadium dioxide-containing particles.

Method for producing vanadium dioxide-containing particle and dispersion

The invention discloses an iron and sulfur removing technology for a sodium aluminate solution based on a recyclable sulfur removal agent. The iron and sulfur removing technology comprises the following steps: (1) adding the iron-based sulfur removal agent in the sodium aluminate solution containing S2- and Fe, carrying out solid-liquid separation, and obtaining the sodium aluminate solution removed from sulfur-removing residues and ferrous sulfide; (2) mixing the sulfur sulfur-removing residues with an alkaline solution to prepare slurry; (3) adding and/or introducing an oxidizing agent to the slurry; (4) conducting liquid-solid separation to the slurry after oxidation reaction, obtaining the regenerated sulfur removal agent and the sulfate-containing solution, and using the regenerated sulfur removal agent for removing sulfur in the sulfur-containing sodium aluminate solution in the step (1); (5) adding a precipitant to the sulfate-containing solution; (6) carrying out liquid-solid separation to the slurry after precipitation reaction, obtaining sulfate precipitated slag and the alkaline solution, and using all or a part of alkaline solution for regeneration and treatment of the sulfur removal agent in the step (2). According to the iron and sulfur removing technology for the sodium aluminate solution based on the recyclable sulfur removal agent, the iron-based sulfur removal agent can be recycled and circularly used for sulfur removal of the sulfur-containing sodium aluminate solution.

Iron and sulfur removing technology for sodium aluminate solution based on recyclable sulfur removal agent

The invention discloses a surface-modified aluminum hydroxide and a preparation method thereof. The surface-modified aluminum hydroxide comprises, by mass, 30 parts of aluminum hydroxide and 0.3-1.2 parts of a modifier. The modifier is Span, a complex of Span and stearic acid, or a complex of Span and sodium stearate. The Span is Span 40, Span 60 or Span 85. The preparation method comprises the following steps of preparing an aluminum hydroxide aqueous suspension having a mass concentration of 10%, heating the aluminum hydroxide aqueous suspension to a temperature of 80-85 DEG C, preparing a modifier-ethanol solution having a modifier mass concentration of 1%, adding the modifier-ethanol solution into the aluminum hydroxide aqueous suspension, heating the mixed suspension to a temperature of 70-90 DEG C, keeping the temperature for 0.5-1.5h, and carrying out standing, suction filtration, washing, drying and grinding so that the surface-modified aluminum hydroxide which is conducive to uniform dispersion in a polymer base and improves base compatibility is obtained.

Modified aluminum hydroxide and preparation method thereof

Method for preparing high-whiteness aluminium hydroxide micropowder from Bayer process sodium aluminate solution

A purification method of a high-concentration sodium aluminate solution from a Bayer process comprises heating the high-concentration sodium aluminate solution to 80-120 DEG C, strongly mechanically stirring, adding a purifying agent into the sodium aluminate solution to desilicate and remove iron, organic substances and colored substances in the solution, and filtering to separate silica residue from insoluble substances to obtain the purified and decolorized sodium aluminate solution with absorbance lower than 0.30. The purifying agent is calcium oxide, magnesium oxide and/or calcined dolomite. The inventive method can perform deep desilication, remove iron and remove colored organic substances by one-step method.

Purification method of high-concentration sodium aluminate solution from Bayer process

The invention discloses a preparation technology of highly pure alumina powder. The technology comprises the following steps: carrying out solution two-stage purification on a raw material industrial sodium aluminate solution or sodium aluminate solution obtained through alkali dissolution blending of the industrial aluminum hydroxide to obtain a pure sodium aluminate solution; adding a crystal seed initiator and a sodium precipitation inhibitor into the pure sodium aluminate solution to prepare a crystal seed slurry; adding the sodium precipitation inhibitor and other impurity inhibitors into the pure sodium aluminate solution, adding the crystal seed slurry, and carrying out species separation at a high temperature to obtain pure aluminum hydroxide; and carrying out high temperature calcining on the pure aluminum hydroxide, carrying out water quenching, and washing to obtain the highly pure alumina powder with the purity of above 99.99% and the average particle size of below 10[mu]m, wherein the highly pure alumina powder is pure alpha-Al2O3 phase. The technology comprises the processes of solution purification to remove slag, species separation of a mother liquor, and entrance of a washing liquid to a Bayer process system. The highly pure alumina powder can be prepared in a low cost, high efficiency and environmental protection manner.

Preparation technology of highly pure alumina powder

The invention discloses a preparation technology of highly-pure ultrafine alumina powder. The technology comprises the following steps: carrying out solution two-stage purification on a raw material industrial sodium aluminate solution or sodium aluminate solution obtained through alkali dissolution blending of the industrial aluminum hydroxide to obtain a pure sodium aluminate solution; adding a crystal seed initiator and a sodium precipitation inhibitor into the pure sodium aluminate solution to prepare a crystal seed slurry; adding the sodium precipitation inhibitor and other impurity inhibitors into the pure sodium aluminate solution, adding the crystal seed slurry, and carrying out species separation at a high temperature to obtain pure aluminum hydroxide; carrying out short time activation roasting on the pure aluminum hydroxide, and washing to obtain highly pure active alumina; and carrying out high temperature calcining on the pure active alumina, and washing to obtain the highly-pure alumina powder with the purity of above 99.99% and the average particle size of below 5[mu]m, wherein the highly-pure alumina powder is pure alpha-Al2O3 phase. The technology comprises the processes of solution purification to remove slag, species separation of a mother liquor, and entrance of a washing liquid to a Bayer process system. The highly-pure ultrafine alumina powder can be prepared in a low cost, high efficiency and environmental protection manner.

Preparation technology of highly-pure ultrafine alumina powder

The invention discloses a deep purification technology of a high concentration sodium aluminate solution. The technology adopting an industrial sodium aluminate solution as a raw material comprises the following steps: applying an electric field, adding an oxidant to make iron and other impurities generate insoluble precipitates, and removing organic matters; adding lime to remove silicon in order to generate hydrogarnet for adsorbing the above impurities, and adding a flocculating agent to further remove iron, silicon and organic matters in the obtained solution in order to obtain a first stage purified solution; adding a precipitating agent into the first stage purified solution, adding an adsorbent, standing, and filtering to obtain a second stage purified solution; and carrying out deep filtration on the second stage purified solution by adding macroporous anion resin in order to obtain a highly pure sodium aluminate solution. Deep purification of the sodium aluminate solution can be realized in a low cost, high efficiency and environmental protection manner.

Chen Xianggen

Papers

Method for preparing high-whiteness aluminium hydroxide micropowder from Bayer process sodium aluminate solution

Purification method of high-concentration sodium aluminate solution from Bayer process

Preparation technology of highly pure alumina powder

Preparation technology of highly-pure ultrafine alumina powder

Deep purification technology of high concentration sodium aluminate solution