RU2602559C1 - Installation for dehydration of ore or coal flotation concentrates - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to mining, processing and concentration of minerals and can be used in coal, mining and chemical industries for dehydration of fine products. Installation for dehydration of ore or coal flotation concentrates consists of two horizontal filtration centrifuges with elastic rotors, frame, electric motor, two squeeze rollers with automatic drives, initial pulp feed and centrate discharge pipelines, v-belt drive. Centrifuge means are mounted towards each other and have a common hopper, common initial pulp feed pipeline equipped with a distribution valve, operating in switching automatic mode in compliance with the cycles time of dehydration in centrifuges. Rotors rotation is performed by an electric motor with two shaft outputs via v-belt drive.

EFFECT: technical result is efficiency increase of dehydration, as well as reduction of solid particles ash with centrate.

1 cl, 2 dwg

Description

The invention relates to mining, processing and mineral processing and can be used in the coal, mining and chemical industries for dehydration of finely divided products with sizes of 0-2 mm

In most ferrous and non-ferrous metals, the useful component is contained in the form of very small grains less than one millimeter in size. Therefore, the technology of their enrichment preliminarily grinds the initial ores to grain sizes (this is necessary for opening the grains), and then they are enriched by various methods. The most effective enrichment methods are wet methods - flotation, wet magnetic separation, enrichment on concentration tables or in jet troughs. The resulting concentrates under these enrichment methods are heavily flooded, that is, one ton of solid contains three or more meters of cubic water. Dehydration of finely ground concentrates to the necessary conditions is associated with great technical difficulties and is a very expensive process. In addition, the use of thermal dryers in dehydration technologies dramatically worsens the ecology of the environment, since a large amount of aggressive gases is released into the atmosphere.

In coal enrichment, dewatering of coal flotation concentrates is also a big problem. Here the difficulty lies in the fact that, on the contrary, due to the softness and brittleness of coal, it spontaneously grinds. When harvesting coal and transporting it to an enrichment plant, the coals of individual mines contain up to 40 percent of finely ground coal with sizes of 0-2 mm. Coal of the indicated sizes is a valuable raw material for coke production; its enrichment is carried out only by the wet method (flotation, screw separators, concentration tables) to produce highly flooded concentrates.

The technology for dehydration of finely ground concentrates in modern coal and ore mills is complex and is carried out using cumbersome and expensive equipment. For example, to dehydrate a coal flotation concentrate or a concentrate of ferrous metal ores, condensation is first used in bulky reinforced concrete thickeners, and then they are dehydrated on vacuum disk filters, which require discharged and compressed air during operation [1].

Disk vacuum filters have a complex device, a large cost (about six million rubles per unit of equipment), a large mass (more than 30 tons), and vacuum filters require constant operation of blowers, vacuum pumps, which cost about one million rubles per unit of equipment and engine power of 100 kW.

Therefore, all over the world there is an active search for new inexpensive effective methods for dehydration of finely ground concentrates. It follows from the foregoing that a technical paradox has developed in the mineral processing and processing industry: highly efficient methods for the enrichment of finely ground minerals have been developed, but there is no engineering solution for the effective dehydration of finely ground concentrates obtained.

Therefore, the development of new effective and inexpensive methods of dehydration of finely ground mineral concentrates is an urgent problem of modern mineral processing. According to the theory and practice of the dehydration process, it is known that the centrifugal forces used in dewatering equipment are tens of times higher than the forces formed by vacuum pumps [2]. Therefore, it is logical to conduct searches in the development of new dewatering equipment for finely ground concentrates in the field of processes using centrifugal forces.

Inertial and vibration filtering centrifuges of the FVI and FVV type are known, sedimentation type centrifuges are also known, but they have significant drawbacks: a complex device, high power consumption, fast wear of rotors, large ablation of solid with a centrate (up to 30%) [2].

A horizontal centrifuge is known (application RU No. 2006112939; November 20, 2007) in which a filter screen is fixed inside the rotor, but it has a significant drawback: the dehydrated material is unloaded with a knife, which leads to quick wear of the screen and its frequent breaks.

A horizontal elastic centrifuge is known (RU 2451558, 2012; bull. No. 15), in which an elastic rubber rotor is used, and the dehydrated material is discharged by centrifugal forces that change their direction by 180 degrees with respect to the direction of action of the dehydrating forces.

By testing this centrifuge model, it was found that it has a simple design, low operating costs, high dehydration efficiency, low solid losses with a centrate and an effective method of unloading dehydrated material without using a knife. Along with the indicated advantages, this centrifuge has a significant drawback: a cyclic mode of operation. That is, during dehydration of crushed materials in this centrifuge, the following technological operations take place sequentially: loading of the initial pulp, dehydration of the material, unloading of dehydrated material. Then the cycle of operations is repeated again.

Cyclic operation dramatically reduces the performance of the centrifuge, complicates its design and necessitates the presence of a buffer tank for accumulating pulp in front of the centrifuge for the duration of the cycle, in which sediment is precipitated and is often clogged. But since the centrifuge is an integral part of the proposed dewatering plant, we take it as a prototype.

The aim of this invention is to develop a simple inexpensive design of a plant for the dewatering of finely ground continuous concentrates with high dewatering efficiency, low solids removal with a centrate and low operating costs.

This goal is achieved by the fact that the installation for dehydration of ore or coal flotation concentrates consists of two horizontal filtering centrifuges with elastic rotors, a frame, an electric motor, two squeezing rollers with automatic drives, pipelines for supplying the initial pulp and output of the centrate, V-belt drive, while the centrifuges are mounted unloading devices towards each other and have a common hopper, a common feed pipe for the initial pulp, equipped with a distribution valve operating in the machine matic mode switching in accordance with the time cycles of dehydration in a centrifuge, and the rotation of the rotors is provided by an electric motor with two output shafts through a V-belt transmission.

The proposed installation for the dehydration of finely ground concentrates (Fig. 1) consists of the following main parts: two elastic rotors, inside which a filter mesh is fixed, two metal housings, one electric motor, two rotor drive shafts, two squeeze rollers, one common feed pipe of the initial pulp, which is equipped with an automatic shutter for switching the pulp supply to centrifuges, one common hopper for unloading the dehydrated material, two pipelines for discharge of the centrate, two for ruzochnyh nozzles, two V-belt drive motor rotational movements.

In FIG. 1 shows a general view of the installation, and FIG. 2 shows a diagram of the unloading of dehydrated material by the action of centrifugal forces of the opposite direction, which occur when the squeeze roller is pressed on the outer surface of the rubber rotor.

The proposed installation for the dehydration of finely ground concentrates works continuously. Continuity of operation is ensured by two horizontal centrifuges with elastic rotors, in which the dehydration process occurs alternately, then in one centrifuge, then in the second. The loading of the initial pulp is varied by a valve with an automatic drive that opens the pulp flow to one centrifuge or to another, tuned for a certain time equal to one dehydration cycle. The dehydration cycle consists of three sequential technological operations: feeding the initial pulp to a centrifuge, sludge dewatering, and unloading of the dehydrated sludge.

For clarity of the operation of this installation, we consider the dehydration mechanism (Fig. 1), which occurs in one of the centrifuges, for example, in the right one.

A horizontal centrifuge with an elastic rotor operates as follows. The initial pulp containing particles of finely divided concentrate is fed through a pipe 12, to an automatic valve 13, and then into the internal cavity of the elastic rotor directly to the armored disk 15. The elastic (rubber) rotor 7 is similar to a tire of an automobile wheel, but on the one hand it has an open cavity, and on the other hand has an airtight wall to which an armored disk 15 is bolted 19. The elastic rotor around the entire perimeter of the internal area has numerous holes 3 with a diameter of 3 mm, and inside ora (the inner perforated surface) filtering mesh 2 is secured (nylon, burlap, cloth, etc.).

An armored disk 15 with a rotor 7 is mounted on the drive shaft 18 with a pulley and rotates at a speed of 750-800 rpm, receiving rotational movement from the electric motor 8 through the V-belt drive 11. In addition, for the compactness of the installation, an electric motor with two shaft outputs 9 of the JM 1003 type is used.

The initial pulp containing solid particles of finely divided concentrates, entering the internal cavity of the elastic rotor, is thrown from the armored disk 15 by centrifugal forces onto the surface of the filter mesh 2. The filter mesh has numerous microscopic holes through which water is ejected by centrifugal forces into the metal casing 1, forming a centrate, which forms a centrate, which then discharged through pipeline 4, and solid particles having larger sizes than the holes in the filter mesh are retained on its surface, o Brazing a layer of sediment of solid particles.

The dehydrated sludge is discharged from the rotor by centrifugal forces as a result of a change in the direction of the forces in the opposite direction. The change in the direction of centrifugal forces is achieved by pressing the squeeze roller 16 on the outer surface of the elastic rotor by the automatic device 14.

All parts of the centrifuge are mounted on the frame 6. When the squeezing roller 16 presses on the outer surface of the rotor, a convex waveform forms on its inner surface (Fig. 2) and centrifugal forces appear in the opposite direction, as a result of which the dehydrated sludge is unloaded. The dehydrated sludge is discharged from the centrifuge into the hopper 5, and then onto the conveyor belt 13. In order to avoid getting the dehydrated product into the centrate, a metal partition 19 is installed between the centrifuges.

The value of the centrifugal force is determined by the formula F = mv ² / R, that is, it is proportional to the mass of the sediment, its speed and inversely proportional to the radius of the circle. Since the rotation speed in the centrifuge is constant, the radius-forming waves r when the roller is pressed are tens of times smaller than the radius of the elastic rotor R, and the centrifugal force acting in the opposite direction is tens of times greater than the force acting during dehydration. Therefore, the sediment will be dehydrated and unloaded from the centrifuge by centrifugal forces. The left centrifuge works similarly.

Naturally, in one revolution of the rotor there will not be sufficient dewatering of the sludge. It has been experimentally established that this requires 12-15 rotor revolutions.

If the rotor speed is 800 revolutions per minute, the length of time for the dehydration cycle for 15 revolutions according to the calculations will be 1.1 s. And the unloading of the dehydrated sludge is almost instantaneous, since three rotor rotations are enough to unload the sludge, which in time is 0.2 s. Thus, the full cycle time is t = 3 + 1.1 + 0.2≈4.5 s where 3 is the pulp loading time into the rotor in seconds.

Therefore, the installation of dewatering centrifuges with elastic rotors should work in the mode of switching the feed of the initial pulp after 4.5 s.

With a rotor diameter of 1000 millimeters, a cross-sectional width of 250 mm and a rotor speed of 800 rpm, the design capacity of the centrifuge will be 30 t / h for solid material.

Consequently, the capacity of the installation, consisting of two centrifuges, will be Q = 30 * 2 = 60 t / h, which is at the level of the most productive vacuum disk filters currently used in enrichment plants.

The advantages of the proposed installation of horizontal centrifuges with elastic rotors:

1) simplicity of design;

2) low maintenance, does not require a large number of workers when repairing or replacing a filter cloth (for comparison: to replace a precipitating centrifuge rotor, a team of 4 people and a time of about 4 hours is required. To replace the filter mesh in an elastic rotor, 1 locksmith and 30 minutes of time);

3) during unloading of the dehydrated sludge in the centrifuge, a slight abrasion of the filter mesh occurs due to the absence of friction between the sludge and the mesh;

4) regeneration of the filter mesh is carried out by centrifugal force at the moment of absence of dehydrated sludge on it.

5) three times less solid particles are lost with a centrate compared to other centrifuges, since the filter mesh has microscopic holes that are much smaller than the slots in the slit-shaped sieves of metal rotors;

6) the rotor casing made of rubber is much cheaper than the rotor casing made of slit sieves;

7) the rubber rotor has a longer service life due to the fact that the dehydrated sludge does not come into contact with it, and only the filter mesh wears out, which can be quickly replaced;

8) the selling price of installing two horizontal filtering centrifuges with elastic rotors is 15 times cheaper than filtering installations of a disk vacuum filter of the same capacity.

According to the calculation, the cost of parts of the proposed paired installation of filtering centrifuges with elastic rotors for continuous filtering of ore and coal flotation concentrates is 500-520 thousand rubles.

The presence of the indicated advantages of installing horizontal filtering centrifuges with elastic rotors when introduced into production will significantly reduce the cost of enrichment products due to the low installation price and low operating costs. In addition, by reducing the loss of solid particles removed with the centrate, the yield of a marketable product will increase, and purified centrifuges can be used as recycled water without additional regeneration.

Literature

1. Technique and technology of coal preparation. Reference manual edited by V.A. Chanturia, A.R. Molyavko. - M .: Nauka, 1995.

2. Chuyanov G.G. Auxiliary enrichment processes. Ed. USMU, Ekaterinburg, 2006.

Claims (1)

Installation for dehydration of ore or coal flotation concentrates, consisting of two horizontal filtering centrifuges with elastic rotors, a frame, an electric motor, two squeezing rollers with automatic drives, pipelines for supplying the initial pulp and output of the centrate, V-belt transmission, characterized in that the centrifuges are mounted with discharge devices towards each other friend and have a common hopper, a common feed pipe of the original pulp, equipped with a distribution valve, operating in automatic mode exceptions in accordance with the time of dehydration cycles in centrifuges, and the rotation of the rotors is provided by an electric motor with two shaft outputs through a V-belt drive.

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