For some ore with a large amount of mud, there are often problems such as large consumption of flotation reagents and poor magnetic separation during the beneficiation process. At this time, Xiaobian will remind you of the friendship: Is it the washing process? ?
Washing is a process for treating ore that is cemented with clay or contains a lot of mud, including two operations of breaking and separating. Usually immersed in water medium, rinsed or mechanically stirred (if necessary, adding dispersant), by means of the friction between the ore particles, the ore particles adhered by the slime are dissociated and separated from the clay, called washing .
1. Under what circumstances should I consider washing operations?
(1) The ore contains more mud and contains more water, often blocking the mine silo, chute, funnel and crushing and screening equipment , making the production difficult to sustain, and can be treated by washing method;
(2) The ore needs to be hand-selected or photo-selected, and the slime stains the surface of the ore block, making it difficult to identify. At this time, it is necessary to wash the mine before hand-selection or photoelectric selection.
(3) The original slime and nuggets of some ores are very different in terms of selectivity (such as floatability, magnetic properties, etc.). After washing and separating the mud and sand, they can be treated separately to obtain better selection. index.
2, the importance of washing process
For the long-term weathering of the primary deposits exposed to the surface, the ore particles are surrounded by the decomposition of clay minerals or rocks, forming a cement or mud body, and there are many people on the surface. In this case, prior to sorting, a mineral washing and disintegrating method different from ore crushing is used to separate the mineral monomers, thereby removing the surface particles of the ore particles and preventing unnecessary crushing or over-grinding.
Some washing process using native micro-fine weathering or non-metallic minerals, ore particle surface can purification, is exposed to reflect the nature of the ore in the surface, a rear surface of the adhesion can not only ore particles were removed to obtain purified by itself, but also for the subsequent processing operations Improve conditions (such as flotation). Washing can be used as a preliminary preparation for other beneficiation and purification operations, or it can improve the purity of minerals alone.
3, commonly used washing equipment
There are many kinds of washing equipment, such as cylindrical washing machine, trough washing machine, hydraulic washing screen and so on.
(1) Cylinder washing machine (cylinder washing screen)
Structural composition: The cylinder washing machine is mainly composed of a closed washing cylinder and a double-layer sieve connected to the end of the cylinder. The cylinder is horizontally supported by two rollers on the two steel rings outside the cylinder. The ring gear is rotated by the pinion gear through the ring gear in the middle of the cylinder. A lining plate is disposed on the inner wall of the cylinder along the longitudinal direction, and the lining plate has ribs. The ribs are arranged in a spiral shape, and the pitch is gradually increased toward one end of the sieve to agitate and push the material to be discharged.
Working principle: The ore and the ore water are fed from the inlet of one end of the cylinder, and the water is soaked in the cylinder and impacted and rubbed against each other during the rotation to dissociate the clay and the ore. High pressure water is introduced from the discharge end of the screen and flows in the opposite direction to the ore. The washed clay and fine particles are discharged from the feed end with overflow. The block and granulated material is lifted by the lifting wheel at the end of the cylinder and discharged onto the double-layered cone screen. Washing water is also added to the double layer screen. The cone-shaped sieve is rotated together with the cylinder, and the material is sieved into three grades of coarse, medium and fine. The fine fraction is combined with the washing overflow.
Process requirements: The process factors that have a significant impact on the results of the washing are the cylinder speed and water consumption. Generally, in order to ensure a high washing efficiency and an appropriate processing amount, the number of revolutions used is mostly 0.5-0.6 times the critical number of revolutions. The amount of water used for washing is limited to the extent that the ore is washed. The total amount of water fed to the washing machine should be such that the overflow concentration is maintained at 20%-25%. The high-pressure water pipe installed in the cylinder screen should be sprayed on the screen surface in a longitudinal direction to achieve a good flushing effect.
Scope and characteristics: The cylinder washing machine washes and removes the slime by high-pressure water washing and sieving. It also has the functions of washing and sieving. It is suitable for the treatment of easy-washing and medium-washable ore. The grain size of the ore should not exceed 100mm. .
The advantage of this equipment is that it is stable and reliable, and the washing efficiency is high. After screening through the sieve, three grades of products can be obtained, and the washing and grading tasks can be completed at one time. However, this kind of equipment has a weak effect on the scrubbing and dispersing of mud, and is not suitable for the treatment of ore with less ore and mud.
(2) trough type washing machine
Structural composition: The trough type washing machine is similar in structure to the spiral classifier, except that the blades are discontinuous blade shapes. In a semi-circular chute, two shafts with stirring blades are arranged, the connecting line of the apex is a spiral line, the rotation directions of the two shafts are opposite, and the impeller stirs to cause the ore particles to collide and rub against each other, thereby cleaning the ore. Grain surface.
Working principle: The slurry is fed from the lower end of the tank, the cement body of the mud group is cut and scrubbed by the blade, and the high pressure water fed by the upper end of the chute is washed to separate the clay and the ore. The washed clay material is discharged from the lower overflow tank. The coarse material is pushed by the blades and discharged from the discharge port at the upper end of the tank. The washing time is determined by the length of the groove, the pitch and the speed of the shaft. Under certain working conditions of the equipment, the washing efficiency is also related to the ore supply, the ore concentration and the ore washability.
Applicable scope and characteristics: The trough type washing machine has the function of cutting and scrubbing materials, and has a strong effect on the small mud group. It is suitable for the treatment of difficult to wash ore with less dense ore, medium size and more mud. Ore, such as kaolin pulping and medium-fine grain materials and silica sand washing. The equipment has large processing capacity and high washing efficiency, and is suitable for processing materials below 75mm. The flushing water pressure is required to be 147-196 kPa.
(3) vibrating washing screen
The grid sieve, the rod sieve, the roller screen and the vibrating screen can be used as a washing equipment after being equipped with a pressure flushing water pipe, and is suitable for treating ore having a small amount of mud and a weak cohesiveness.
The sieve is used to screen the ore before coarse crushing, the roller screen is used for sieving medium-sized ore before crushing, and the shaker is used for treating ore before or after crushing. The feed water pressure is generally 0.2-0.3 MPa, and the water consumption is 1-2 m3/t ore. When the raw ore contains little mud and the cohesiveness is not strong, the requirements for washing can be achieved by using these equipments. However, the operation must pay attention to the ore moving into a single layer on the sieve surface, otherwise the ore covered underneath will not be washed.
4. How to choose washing equipment?
The choice of washing equipment and its throughput depends mainly on the washability of the ore. The washability of the ore can be assessed according to indicators such as clay plasticity index, washing time, specific energy consumption and washing efficiency.
5. How to treat the washing wastewater?
(1) Generally, the washing wastewater is mainly treated by coagulation and sedimentation, and the supernatant of the sedimentation tank is recycled. The sand can be used as raw materials for building materials;
(2) The heavy metal washing wastewater contains coagulation, sedimentation, oxidation/ion exchange and other processes to avoid heavy metal pollution.
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