At present, when using producing aluminium oxide by bayer both at home and abroad, adopt the molten technology and equipment of high extrusion to obtain extraordinary effect.Some alumina producers of China have also adopted this technology.There is very strict requirement in this system to the granularity of raw pulp.If pulp granularity is thick partially, after entering in the pressure digestion system, ore pulp is very serious to the wearing and tearing of equipment, can have influence on the work-ing life of single tube preheating tube and autoclave heating tube greatly, in addition, the granularity of raw pulp is thick partially, also makes the high pressure process in leaching produce a large amount of coarse sands, these coarse sands contain the aluminum oxide that a large amount of ends are dissolved, and cause unnecessary waste.More effective former slip preparation method adopts one section rod milling, two sections ball millings to add two sections closed circuit flow processs of mill of swirler group at present, the raw pulp of this method output can guarantee the granularity requirements of process in leaching effectively, and the raw pulp preparation flow that the present many alumina producers of China adopt to be the grid mill add one section closed circuit flow process of mill of screw classifier, the granularity of the raw pulp of preparation is thick partially, does not reach the needs of high pressure dissolving-out process process.For the original alumina producer of China, when adopting high pressure dissolving-out process equipment, need improve the raw pulp preparation method, original one section grinding process of the alumina producer that builds up the sixth of the twelve Earthly Branches be transform as two sections mills add the swirler group many difficulties are arranged, because the floor space that two sections mills add the swirler group is very big, and original equipment occupation of land is narrow and small, how can't carry out the novel process preparation, and need to increase rod mill, investment cost is strengthened, the increase of equipment has simultaneously also increased accordingly the expense that turns round.
Purpose of the present invention is exactly in order to overcome in the existing aluminum oxide production process, the raw pulp preparation method's who exists deficiency, the raw pulp preparation method of a kind of producing aluminium oxide by bayer that proposes a kind ofly to improve grinding machine production capacity, assurance raw pulp size indicator effectively, cut down the consumption of energy, its process unit floor space is little.
A kind of raw pulp preparation method of producing aluminium oxide by bayer comprises the levigate of ore, lime; Add alkali lye slurrying; Size classification is characterized in that pulping process is:
A. at first bauxitic ore and lime are fed in the grid mill with board-like machine, enter pulp tank after the swirler underflow is pulverized grinding, add circulation alkali liquor, it is 1.20~1.70 that slurrying makes its liquid-solid ratio, and solids content is 650~850 grams per liters;
B. by pipeline ore pulp is sent into swirler with feeding pump and carry out particle size separation, the feed pressure of control swirler is between 0.07~0.105MPa, the solids content of the overflow of swirler is 300~400 grams per liters, granularity is+0.25mm≤1%, + 0.094mm≤22%, its underflow solids content is 1000~1500 grams per liters, and liquid-solid ratio is 0.6~0.7;
C. overflow is discharged as qualified raw pulp, and underflow returns the grid ball mill as recycle stock and grinds, and its recycle stock amount is 200~400% with new mine-supplying quantity than (being anti-sand ratio).
Method of the present invention, employing will be through ore and the lime after the grid grinding machine grinds, put into pulp tank with alkali lye, add the alkali lye amount by control, control the solids content that feeds ore pulp and the solid-to-liquid ratio of certain hydrocyclone, promptly guarantee the suitable ore deposit parameter of giving, select suitable operating pressure simultaneously, overflow portion by hydrocyclone obtains being fit to the required raw pulp of high pressure dissolving out process, the underflow sand setting returns add-back grid grinding machine, and the original ore size index that it finally makes can reach+0.25mm≤1%, 0.094mm≤22%, its solids content is 300~400 grams per liters, can satisfy the requirement of high pressure dissolving-out process fully.
Adopt processing method of the present invention, to adopting the enterprise of one section grinding process at present, adapt to high pressure stripping requirement, the preparation method improves to raw pulp, especially to the factory site condition do not possess enterprise, be more suitable for adopting method of the present invention, promptly can produce qualified raw pulp, saved the screw classifier that production capacity is low, heavy, maintenance capacity is big, saved manyly than two sections mill+swirlers in the investment.
Below in conjunction with example method of the present invention is described further.
Bauxitic ore and the lime that accounts for the particle diameter ≯ 50mm of ore weight 8~12% with granularity≤20mm, with entering pulp tank after the grid grinding machine pulverizing grinding, add circulation alkali liquor, it is 1.20~1.70 that slurrying makes its liquid-solid ratio, solids content is 650~850 grams per liters, by pipeline ore pulp being pumped into divider with feeding pump advances swirler respectively and carries out particle size separation, classification, the feed pressure of control dispenser is between 0.07~0.105MPa, the solids content of the overflow portion of swirler is 300~400 grams per liters, granularity is+0.25mm≤1%, + 0.094mm≤22%, its underflow solids content is 1000~1500 grams per liters, liquid-solid ratio is 0.6~0.7, and overflow is discharged as qualified raw pulp, and underflow returns the grid ball mill as recycle stock and grinds, its recycle stock amount be 200~400% newly to the ore pulp ratio, the solids content that gets raw pulp is 379.65 grams per liters, and+0.25mm is 0.34%, and+0.094mm is 10.81%.