Mineral sizers is a kind of crushing equipment appearing in foreign countries in recent years. Compared with other types of crushing machines, mineral sizers has the advantages of light weight, small size, low power consumption, high productivity, uniform discharge particle size, etc. It is especially suitable for crushing stations in open pit mines and gravel crusher for road construction. At present, the domestic demand for the equipment is very large, due to the introduction of expensive, so its technical digestion and absorption has become the current urgent task. On the basis of analyzing the crushing and discharging mechanism of mineral sizers, the formula for calculating the production capacity of this kind of equipment is derived for the first time, and the determination method of prime mover power is proposed. 1. Mechanism analysis of crushing and discharging
Mineral sizers main working parts are two parallel mounted tooth rolls, each tooth roll along the axial arrangement of a certain number of tooth rings, through the tooth roll to achieve the crushing of the material. The action process of teeth on materials can be divided into three stages. In the first stage, the roll teeth in the rotating motion encounter a large material, which is first subjected to impact shear and then torn. If the fragments can be bitten by the roller teeth, it enters the second stage of crushing, otherwise the roller teeth slide forcibly along the surface of the material, forcing the material to turn over by the spiral arrangement of the roller teeth, waiting for the continued action of the next pair of teeth. The first stage is the tooth from 1'-1 position to 2'-2 position. The second stage begins with the material being bitten and ends with the first pair of teeth breaking away from the bite, showing the process of tooth movement from the 2'-2 position to the 3'-3 position. At this stage, the cross section of the two teeth is gradually changed from large to minimal, and then increased. The large particle size is forced to be squeezed and cut because the containing volume is gradually smaller, and the broken material is extruded and leaked from the tooth side gap.
When the first pair of teeth begin to disengage, a large number of broken materials leak out, and individual materials with large particle size are blocked by the splitting rod. When the teeth move near the splitting rod, they work together with the splitting rod to break up the large material and force it out, which is the third stage of crushing. At this point, the crushing process of a pair of teeth is over. How many teeth there are on each pair of tooth rings, the same process is carried out how many times when the tooth roller runs for a week, and the cycle is repeated.

2. Mineral sizers calculation of production capacity
Production capacity is an important indicator of mineral sizers performance. It is directly related to the selection of parameters in mineral sizers design, such as the determination of power, and is also an important basis for user selection. Therefore, how to determine the production capacity of mineral sizers is very important. From the crushing and discharging mechanism of mineral sizers, it can be seen that:
(1). Mineral sizers have forced bite characteristics and forced discharge characteristics, which is different from the general roll crusher, so it is not simple to apply the production capacity calculation formula of roll crusher.
(2). When the roller speed is constant, the production capacity of mineral sizers depends on the ability of the tooth roller to bite into the material during operation. This ability depends on two factors, one is the geometry of the teeth, that is, the area of the closed polygon formed by the two pairs of teeth. The other is the mineral and rock characteristics of the material, the easier the material is to crush, the closer the amount of each bite is to the maximum allowed by the geometry of the tooth roll. From this, we get the following formula for calculating the theoretical production capacity q: q=60 m k n a 1 (m'/h)(1) : m is the number of teeth on the circumference of the gear ring; k is the characteristic coefficient of mineral rock; n is the speed of tooth roll, r/min; a is the closed polygon area formed by two pairs of teeth at the front and back, 2 m, 1 is the length of teeth spread along the tooth roll axis, m. Considering that part of the material leaks from the gap of the teeth, it should be compensated. The compensation amount can be calculated by the calculation formula of the production capacity of the roll crusher: q=3600vfu(m3/h)(2) : v is the average linear speed of the crusher roll teeth, m/min; f is the area of material passing between the crusher roll teeth; u is the material looseness coefficient, which is 0.25 to 0.4. the production capacity calculation formula is as follows: q=60 m k n a 1+3600vfu(m/h)(3) the meanings of symbols in formula (1) and (2). Formula (3) is applied to calculate the production capacity of 1250mineral sizers. The lower limit of theoretical production capacity is obtained when k0.75 and positive 0.25. when k=1.0,0.4, the upper limit of theoretical production capacity is obtained, and the result is highly reliable. The selection of k value can borrow the filling coefficient of the primary crusher.