SU874119A1 - Method of filtering polydispersed suspensions - Google Patents

Description

(54) METHOD OF FILTERING POLYDISPERSE SUSPENSIONS

one . .v The invention relates to methods for filtering polydisperse suspensions on bulk-type filters, in which the movement of the force of gravity coincides with the movement of the filtrate and may be used in chemical, coal, mining and other related industries. There is a known method of filtering polydisperse suspensions with a preliminary separation into coarse and fine particles and feeding a large part to the filter septum followed by feeding the fine part to it and filtering them together. The disadvantages of the method are the lack of adjustment of the height of the sediment layer of the coarse-grained part, as well as in the use of expensive flocculation, lnta. The lack of adjustment of the height of the coarse-grained part of the layer leads to the fact that, at its low heights, the fine part, penetrating through its pores, clogs the filter septum and this leads to the termination of filtration. With greater heights (volumes) of the coarse-grain layer, the total filtration resistance increases, which leads to a decrease in the filtration rate and an increase in the moisture content of the sediment. The flocculant treatment of the fine part leads to an increase in the viscosity of the liquid phase, which reduces the filtration rate and increases the moisture content of the precipitate. The purpose of the invention is to develop such a method for filtering half-permeable suspensions, which would allow to increase the filtration rate and reduce the moisture of the sediment without using flocculant. In order to achieve this goal, the initial polydisperse suspension is divided into coarse and fine particles in the ratio (): 1. After that, a layer of coarse-dispersed part with a height of 30-50 mm is applied onto the filter septum, and then a fine part is fed and filtered. With this filtration of the polydisperse suspensions, an optimum filtration rate is achieved and the possibility of blocking the filter septum is eliminated. The minimum height of the layer of 30 mm of the coarse part is due to the fact that with a lower height of this layer, particles of the fine part of the suspension penetrate through the layer, clogging the filter septum. As a result, the filtering rate decreases sharply or the process stops altogether. When the layer of the coarse-dispersed part is more than 50 mm high, the total resistance to filtration increases sharply, as the volume increases (the height of the common layer). . It should be noted that when filtering a small volume of the fine part through a layer of more than 50 Mm, the filtration efficiency does not decrease. But, since the Fine part is separated from the total mass of the polydisperse suspension, the larger the volume of the coarse part, the smaller the fine part. However, this reduces the average size of the part of the fine layer, which leads to a sharp increase in resistance. Poetsdaw the volume of the fine part of the suspension should be 1/2: 1/3 of the coarse, with a height of the last 30-50 mm. In order to ensure such a ratio of coarse and fine parts, the initial suspension must be separated in a hydrocyclone with an appropriate degree of extraction of the coarse part.

Selection of the height of the coarse-grained layer. the side of reduction or increase in the chosen limits must be made on the basis of the amount of the fine part. With a small amount of the finely dispersed part, the layer of the coarsely dispersed part can be increased, while with a larger amount of the finely dispersed part, it can be reduced.

The proposed filtering method can be effectively applied to the filter:

+0.5 +0.31

Coarse h. 59.77 20.72 Fine h. 0,00 0,96

The table shows the filtration process of the polydisperse suspension.

bulk pax, i.e. The condition must be met that the direction of filtering coincides with the force of m, tin.

Example. Before filtering a polydisperse suspension (for example, flotation tailings of potash production) having the following fractional composition: coarse part (particles more than 140 µm) - 65%, fine part (particles less than 140 µm) - 35%, - it is separated on a hydrocyclone to the coarse dispersion ratio : finely divided part in 2.5: 1. Thus, when separating 100 kg of solid particles of the suspension, 71.5 kg of particles are in the coarse part, and 28.5 kg in the finely dispersed part.

The coarsely dispersed part consists of 63.5 kg of particles + 100 µm and 8.0 kg of 4100 µm). In the fine part there are 1.5 kg of particles + 100 µm and 27.0 kg - (-100 µm).

When filtering this suspension by the proposed method with a total height of 60 mm, the filtration rate is within O, 218 "10 0.537-10 m / m s.

To compare the performance of the filtration process using the proposed method, experimental work was carried out using a belt filter ;; with a converging web of type L 2.50, 5 K, which are presented in the attached table. The flotation tailings of the Stebnikovsky potash plant were used as a suspension. FilteraaHHe was conducted at.

At l. ,

The granulometric composition of the following parts, mm:

+0.14

Claims (1)

+0.04 -0.04 4.21 6.47 2.81 27.73 66.30 3.68 The advantages of this filtering method are an increase in the filtration rate, a decrease in the moisture content of the sediment, and no flocculation. This makes it possible to increase the efficiency of the filter unit, as well as reduce production costs. . Claims A method of filtering polydisperse suspensions, carried out by pre-separating the suspension into coarse and finely dispersed. Continuing the table, the persistent parts and the bottom and the filter septum are first coarse and then finely dispersed. also eliminating flocculation, the separation of the suspension is carried out to the ratio of the coarse fine particles {3.2) r1, and the filtration is carried out at a height of lo krupnodispersyoy part of 30-50 mm. Sources of information taken into account in the examination 1. USSR author's certificate 421343, cl. В 01 D 37/02, 28.03.72.