SU580825A3 - Method of pretreatment of aluminium-containing ores - Google Patents

Description

The process can be accelerated if the treatment is carried out with alkali heated to 50-90 ° C, since the sizes of the capillaries and channels of the ore grains are constantly increasing and, consequently, the ability to absorb large amounts of alkaline liquid increases. If the grains are kept in an alkaline solution, they absorb more of the liquid and soak it. Practically, the ore grains are moistened to such an extent that after a certain time, the ore pieces disintegrate and can be easily destroyed, which allows the operation to be crushed to the desired degree. This operation can be carried out using a conveyor grinding pump or the grinding operation can be omitted altogether, since it is carried out during the transportation of this suspension. As a result of pretreatment of the ore, the degree of Moss hardness can be reduced from 5 to 1-2; at the same time, the sharp corners and edges of the crystals become dull, the structure of the pieces of aluminum ore weakens and becomes spongy. Ultimately, pieces of bauxite are destroyed with much less energy, and the abrasive wear caused by them is reduced. Thus, the described process can be performed with a grinding and transporting pump. After pretreatment of the bauxite for a sufficient time in the aqueous alkali solution, slots are formed, which do not need to be kept for a long time in the grinding system (which is necessary if bauxite is used). It is best to use transporting pumps with a shaft rotation speed of 700-3000 rpm. Such pumps are used in industry for grinding materials with a soft structure, for example, asbestos, waste, solid components of wastewater, leather, cellulose, paper, pharmaceutical products in the food industry. A disk rotor pump can be used, for example, a Horator pump, as well as a pump with rotating blades of the type disintegrator, which serves to grind bentonite. For this purpose, other pumps based on the effect of shearing and / or tight compression can be successfully used, for example, centrifugal or screw pumps developed for the production of grinding. In addition, ball mills can be used to obtain the required grain size of the pretreated slurry from ore and alkali. In this case, after grinding, the grains are separated from the slit, the size of which does not meet the required size, and is recycled to the pump suction piping. It is also possible to use such a combination when the raw grains are fed to two successive pumps that are designed to produce grains with the required sizes. It is advisable to add an alkaline solution before the operation of pre-crushing pieces of bauxite in order to wet the ethyl pieces, which simplifies the process of pre-crushing. In such cases, it is difficult to determine in advance the time required for the passage of bauxite in an alkaline environment, since the sizes and properties of bauxite ore are different. However, the pre-crushing operation is easier if the bauxite is longer in contact with alkali. If the pre-crushing operation is carried out with dry bauxite, the resulting grains with a diameter of 20-30 mm are mixed with a portion of the alkaline solution used for the crude extraction, resulting in gaps with good qualities. The relatively uniform distribution of grain sizes in the slurry makes it easy to set the predissolution and wetting time. For the pre-crushing operation, there is a very advantageous embodiment of the proposed method, in which pieces of raw bauxite interact with an alkaline solution already at the production stage of bauxite ore and ore, obtained after pre-crushing. Bauxite is transported hydraulically directly from the pipeline through the pipeline to the surface and enters the mill for grinding. The preparation of the slurry and the pretreatment with an alkaline solution are also carried out on the surface, where grinding takes place with the aid of grinding pumps. In addition, it is possible to transport crude bauxite ore suspended in an alkaline solution, hydraulically through a pipeline to an aluminum plant, where it is processed with a grinding pump. In this case, the pretreatment operation is associated with the effect obtained from transporting hydraulically. In this way, since the time required for the pretreatment of bauxite with an alkaline solution is determined by the time it is transported by pipeline; on the other hand, transporting a suspension formed in an alkaline solution through a pipeline represents a more modern and cost-effective solution compared to all other surface-carrying means on the surface. It is preferable to hydraulically transport the bauxite caged in the alkaline solution, provided that it is transported in the form of suspended large pieces through the pipeline only to a distance which takes several minutes to dissolve and wet. This is followed by a grinding operation with grinding pumps, resulting in a suspension containing bauxite with a grain size of about 1-2 mm, which is not pumped hydraulically through the pipeline. In this case, much less energy is required. Transportation of the suspension with small grains through the pipeline can be performed by means of conventional pumps. At this stage of transportation, bauxite ore, consisting of grains of 1-2 mm in size, is under the influence of an alkaline medium for a certain time, as a result of which

very fine grains with a size of 10 microns reduced fatigue equipment.

The ratio of the amounts of bauxite and alkaline solution can be adjusted with the help of an automatic device, regulating its amount of sludge, and it is necessary to prepare sludge with such a quantity of mud, at which grains are covered with it over its entire surface; The sludge density allows it to be transported using a chopping pump.

It is advisable to carry out pretreatment in such a way that cracks are obtained with 65-35 ° / oh alkaline solution content necessary for carrying out the entire extraction process, although such processing can be carried out with the whole amount of alkaline solution as a whole. The pretreatment time during which the bauxite grains are in contact with the alkali solution is adjusted so that the pieces of bauxite disintegrate and moisten it to the desired degree. The screw transport system, in which direct contact is made between pieces of bauxite, contributes to the success of the described process. It is also advisable to prepare sludge at an alkaline solution temperature of 50-90 ° C, which increases the effect of the extraction process.

Depending on the duration of the pre-treatment and the intensity of the contact, the quality and efficiency of the grinding operation can be increased, as well as the abrasive effect of the ore particles on the grinding pump can be reduced. In some cases, when the pretreatment time exceeds 60 minutes, the raw material obtained at the outlet of the chopping transfer pump can immediately enter the tank, which serves to remove silicon dioxide containing, without pretreatment and slurry classification. In the case of a shorter treatment time, t. 25-30 minutes, only 15-20% of the solids obtained at the outlet of the chopping transfer pump must be sent for recycling through the closed loop of this pump in order to obtain the required sizes of the indicated particles. The required particle size can be obtained in a closed circuit of a hydrocyclone by passing the slime under a pressure of 3-5 atm through a battery containing two-row hydrocyclones connected in series. The resulting precipitate in hydrocyclones returns to the grinding pump, and the suspension in the upper part of the hydrocyclone goes to a further processing stage, i.e., to a tank designed to remove silicon dioxide.

Moistening the bauxite with an alkali solution during the pretreatment process and subsequent grinding with grinding pumps are performed in different ways.

FIG. 1 is a schematic of a process in which the grinding of pre-treated bauxite is carried out in two stages with

relief from a chopping pump: in diagram 2, in which the pretreated bauxite is crushed by means of a chopping pump, followed by size 1; particles of the slime are adjusted to the required.

Bauxite (B) enters the tank 1. In the first embodiment of the proposed method (see FIG. 1), the sludge enters the tank, the passage is the operation of pre-crushing, after which its grains have a size of 20-30 mm. According to the second option

0 (see Fig. 2) the starting material is not subjected to the operation of pre-crushing; it is assembled in pieces with various sizes. In the tank 1 add such amount of alkali solution to cover the pieces

5 bauxite. It is desirable to have a crushing roller in the tank to crush bauxite entering this tank.

Crushing rollers are chosen so that with different processes get the grain with the desired size. For example, in the case of the second option, the bauxite entering the reservoir I is crushed in the wet phase with crushing rollers, first in the raw, unprocessed form, and then with the aid of crushing rollers located in the second tank, into which bauxite slots are fed; The ore from 5 is reduced to 10 mm grains. The presence of a process tank 1 with crushing rollers or other means of grinding installed in it is not necessary, but they are convenient because they pre-crush pieces of the sieve weakened during the pre-treatment process, resulting in easier operation and increased pump efficiency intended for direct grinding of bauxite. When used, the load becomes universal. The bauxite slurry flows from tank 1 into screw conveyor 2, 1 each, which is pulverized into pump 3. The drawings show the case where bauxite slime is formed and the grains decompose as a result of finding bauxite for a sufficient time in one or more process tanks. x pretreatment. In addition, the process equipment operates continuously. Bauxite and alkaline aqueous solution continuously flow into one or

5 several process tanks 1. The disintegration period is determined by the required residence time of the sludge in these tanks, after which the required amount of sludge is taken from the process tank. The second option provides

Claims (3)

0 simultaneous operation of the process equipment charged in portions with a mixture of bauxite with an aqueous solution of alkali, while the slag obtained from the bauxite ore in consecutively operating units of the process equipment, which passed the pretreatment stage, enters the grinding pump 3; in parallel, an operation is carried out to pretreat and moisten bauxite in an aqueous alkali solution. If the humidification period lasts 60 minutes and four consecutive pieces of equipment are in operation, each unit is individually loaded and discharged in portions every 20 minutes, and the load quantity corresponds to the amount of fluid that the grinding pump can pump in 20 minutes. In accordance with the process shown in FIG. 1, the slurry after pre-wetting with a certain amount of an aqueous alkali solution is supplied by means of a screw conveyor 2 to series-connected grinding pumps 3. Bauxite, subjected to preliminary crushing to grain sizes of 10 mm and, accordingly, weakened as a result of moistening, is ground by a first grinding pump, which is a rotary disc pump type Horator, depending on the setting of the pump to the grain with a size less than G mm. Thereafter, the resulting slurry is fed to the next grinding pump, the presence of which is determined by the required grain size. Serial connection of two or more grinding pumps is not a prerequisite for the implementation of the proposed method, since after a 60-minute moistening process with repeated treatment of bauxites with a high content of hydrargillite, a suspension with the required grain size is obtained using a grinding pump adjusted to obtain the required grain size. It is advisable to use recirculation on all grinding pumps, which allows to regulate the amount of pumped mud, and on the other hand, to obtain uniform grinding. After the grinding pumps 3, the remaining part of the total volume of alkali solution required for the extraction process is added to the bauxite sludge (Sz), after which the solution is drained and subjected to further processing in a known manner. In the second embodiment of the proposed method, the slit flows from the screw conveyor to the grinding pump 3; It is advisable to pre-moisten the sludge with an additional amount of alkaline solution. Using a chopping pump 3, the pretreated and wetted slots containing bauxite with grain sizes of 10-20 mm are crushed to the required degree, with a part of this material being recycled, after which the sludge flows into the battery of hydrocyclones 5, where its particle size is adjusted to the required. The slurry pump transports the slurry with crushed bauxite at the required pressure of 3-5 atm to a slurry installation consisting of one or several hydrocyclones, after which the bauxite remaining at the bottom and consisting of particles with a larger size is recirculated to the suction line of the grinding pump. An alkaline solution (L) is added to the sludge (Sz) containing finely ground bauxite, resulting in a desired amount of alkali required for extraction. Next, the sludge enters to perform the next operation, for example, to remove silicon dioxide, etc. It is advisable to unload each process tank 1 by means of a screw conveyor 2 and feed the sludge to the next process tank 1 or the grinding pump 3, since this eliminates the possibility of rapid removal alkaline water solution from the process tank; The composition of the bauxite rock is the same. If the pretreatment of bauxite is performed hydraulically before the crushing operation in the presence of an aqueous alkali solution in the pumping pipeline, the slots containing lump bauxite enter the shredding transfer pump 3, from where the sludge is fed directly to the grinding pump 3, which is adjusted to obtain the required dimensions grains, or by means of a slurry pump 4 (see Fig. 2) - into a slurry receiver consisting of a battery of hydrocyclones 5. Example. 6.3 tons of bauxite (Iskazazentgorgi, Vengri) containing 50.5% of a module equal to 8.2 (Alp.j: SiO ratio) are pre-crushed to grains with a maximum size of 30 mm and shifted from a 7.3 m aluminate solution sodium with a temperature of 54 ° C, containing 190.2 g / l and 78.4 g / l AlD, then kept in a container for 30 minutes. Above the upper end of the pipeline of this capacity, the bottom of which has the shape of a pyramid, grinding rollers are installed, rotating in the opposite direction, by means of which bauxite is crushed to a grain size of 10-15 mm for a certain time. At the same time, the bauxite slit enters a screw conveyor located horizontally below the tank. The rotation of the grinding rollers is provided by a belt drive with a certain gear ratio from the screw conveyor to get synchronization of its work. An aqueous solution of alkali with a certain concentration is continuously fed into the slots of bauxite, which is removed by a screw conveyor and is fed into the chorator's chopping pump. The internal space of the pump has a special shape, while the speed of the pump is 1400 rpm and its inlet is horizontal. The leaching solution feed before the grinding pump is adjusted so that the sludge contains bauxite with a concentration of 300 g / l. After the commencement of the grinding operation, the pre-crushed bauxite and the leach solution are continuously sent to the indicated tank in accordance with the yield of 8 tons of bauxite and 10.3 m of the leach solution. With continuous feeding, the wetting time of bauxite in this tank is adjusted to an average of 30 minutes. When testing a raw sludge sample (after passing a grinding pump), the sediment is 6.7% on a filter with a hole diameter of 315 microns and 9.1% on a filter with a hole diameter of 200 microns. If the crushed bauxite gaps are recycled again, the filter residues are 1.2% and 6.6%, respectively. As a result of pretreatment, the aluminum ore is moistened and its structure is weakened, more easily yielded to crushing. Due to this effect, the amount of energy required for grinding is significantly reduced. During pretreatment, the pieces of bauxite are softened to such an extent that grinding of bauxite with ball mills becomes redundant, and grains of the required size can be obtained with a grinding and conveying pump. The abrasive wear caused by the impact of particles on the crushing equipment is reduced due to this pretreatment, as the grains become less solid and the alkaline solution serves as a lubricant. The area required for this process becomes smaller, the yield is better, and the crushing operation preceding the extraction is carried out with much less noise. Formulation formula 1. A method of pre-processing aluminum-containing ores, including their crushing and grinding, characterized in that, in order to intensify the process, simplify it and reduce it, after oh the blend, the ore is exposed to alkali for 12 minutes to 12 hours. 2. Method according to .1. 1, characterized in that during exposure to alkali, the ore is crushed to a particle size of less than 30 mm. 3. Method according to paragraphs. I and 2, characterized in that the alkali is preheated to FG-90 ° C. Sources of information taken into account in the examination: 1. Liner A. I. Alumina production. M., GOSNTI literature on ferrous and nonferrous metallurgy, 1961, p. 141 -188.