High efficiency magnetic separation of quartz sand

This paper introduces in detail the high efficiency magnetic separation process of quartz sand and the series of equipment adopted.
 
Due to the influence of environment, it is impossible to produce high-purity quartz sand by flotation, acid leaching and other methods in some areas, so it is necessary to use pure physical methods to reduce iron and purify quartz sand. The traditional method of quartz sand magnetic separation and purification uses a large number of strong magnetic rods (the surface field strength is 0.8T) placed in the ditch and cleaned in turn manually to achieve the purpose of iron removal, which not only has a large workload of workers, but also is difficult to control in production. Because of the small magnetic force and the material can not contact with the surface of the cylinder, the traditional drum magnetic separator has a poor effect of iron removal in the production of this kind of quartz sand. With the increase of using time, the magnetic field will be attenuated.



Sinonine combines with silica sand processing plant, reasonably arranges magnetic separation equipment and grasps an efficient magnetic separation process. The sand washing plant can greatly improve the purity of quartz sand, with zero discharge, no waste, no pollution, high production capacity and low energy consumption per unit. It can be applied to large-scale quartz sand production line.

The specific production steps of the sand washing plant are as follows:

1. Crushing and washing

The quartz ore is crushed to less than 5cm by jaw crusher, and then it is crushed to about 1cm particles by cone crusher. The ore is transported to the vibrating screen by belt conveyor, and the fine ore on the vibrating screen is washed by sand washing machine to remove the clay and other impurities on the surface of the fine ore. the materials under the screen are desliminated and concentrated by the desliming cone to obtain ordinary quartz sand; the overflow of the desliming cone enters into the thickener.


2.Grinding and primary classifing

The washed quartz ore is first sent to the rod mill for wet grinding to slurry, and the slurry enters to the rotary drum screen  for the first classification of 20 mesh, and the materials >20mesh are transported to the rod mill for regrinding by belt conveyor.


3. Desliming

The underflow pulp from the rotary drum screen enters the desliming cone to remove the mud and mica light debris, and the overflow of the desliming cone enters the thickener.

4.Magnetic separation

The underflow slurry of the desliming cone passes through the drum magnetic separator and the high gradient magnetic separator in turn. The field strength of the drum magnetic separator is 0.1-0.5t, which is mainly used to remove the strong magnetic minerals in the quartz sand and the mechanical iron in the processing. The background magnetic field strength of the high gradient magnetic separator is required to reach 1.0-1.5t, the medium is 1.5mm rod, and the ore feeding concentration is controlled at 10-15%, which is used to remove the weak magnetic minerals such as biotite, Fe2O3 and TiO2 in the sand, the tailings after weak magnetic separation and strong magnetic separation are magnetic substances, which can be used as the by-product of raw material sand for rabbit fired brick.



5.Secondary classifing

After the magnetic separation, the mortar is graded by the hindered settling classifier and hydraulic classifier. By adjusting the size of the valve at the bottom of the hydraulic classifier and the backwash water, the customer's demand for different particle products can be realized.



6.Dewatering

The underflow and overflow slurry obtained by the secondary classification of the hydraulic classifier are concentrated and dehydrated by the high frequency dewatering screen. After the underflow slurry is concentrated and dehydrated, the high-purity quartz sand products (including SiO2 > 99.8%, Fe2O3 < 0.007%, Al2O3 < 0.2%) are obtained. After the overflow slurry is concentrated and dehydrated, the refined quartz sand is used as raw materials for ceramic glaze.



7. Tailings disposal

The tailings from washing and desliming cone in the process are all sent to the thickener. They are first concentrated in the thickener and then filtered by the ceramic filter. The filter residue is used as the by-product of cement raw materials.


This sand washing plant has the following technical advantages:
 
1.Two stage crushing (coarse crushing, fine crushing) and rod mill grinding are adopted to overcome the disadvantage that only one stage crushing, which greatly improves the production capacity and reduces the unit energy consumption, and is suitable for large-scale production.

2.In terms of magnetic separation equipment, in addition to the drum magnetic separator, the high gradient magnetic separator is also used. The high gradient magnetic separator not only has large magnetic field strength and high gradient, the key is to configure a pulsating mechanism, which can repeatedly separate weak magnetic minerals in quartz sand and intergrowth quartz with high iron content, and remove them to the greatest extent, so as to improve the quality of quartz sand purity.



3.The tailings are treated reasonably, which not only saves water, but also makes the filter residue as the by-product of cement raw material, so as to achieve zero discharge, no waste generation and no pollution.

4.This quartz sand magnetic separation process is simple, easy to operate, low cost, high purification efficiency, the product performance is stable, the production environment is friendly, the whole production process does not use any chemicals, and does not produce any waste water, waste residue and waste gas.