Home Uncategorized Application and development of complete equipment for impact ultrafine crushing and classification

Application and development of complete equipment for impact ultrafine crushing and classification

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Yin Xiaodong, Qi Fengyuan, Guo liwang Changhui, Tan Yong, Ma Liang, Yang zhanhou, Wang Xinjiang

(Xianyang nonmetallic mine research and Design Institute, Xianyang 712021)

abstract through the introduction of the principle and application of CXF series impact superfine mill, combined with the development of relevant technologies at home and abroad, the development objectives and trend of Impact Superfine Mill are put forward

keywords ultrafine powder; Impact mill; Development direction

Introduction to the first author: Yin Xiaodong, male, born in 1960, President of Xianyang nonmetallic mine research and Design Institute, professor level senior engineer. Tel: 029-33343053; E-mail:@sinoma。

1. Overview

up to now, the ultra-fine grinding methods are mainly mechanical methods, including air mill impacted by high-speed air flow; Impact superfine pulverizer using high-speed mechanical rotary impact and shear action; Stirring ball mill, vibrating ball mill, rotary ball mill and planetary mill using friction grinding; Colloidal mill using shear force; High pressure roller mill using compressive stress; And jet crusher impacted by high-pressure jet

Xianyang nonmetallic mine research and Design Institute, as one of the earliest units to carry out ultra-fine crushing technology research in China, has developed CXF series complete sets of impact ultra-fine crushing and classification equipment. The equipment is recognized by the majority of users because of its low energy consumption, high crushing efficiency and stable product quality. At present, more than 300 sets have been sold all over the country and exported to Africa. They are widely used in the ultra-fine grinding of non-metallic minerals such as talc, kaolin, calcium carbonate, serpentine, magnesium oxide and barite [1 ~ 5]

II. Structure principle

cxf51 A-type ultra-fine grinding complete equipment is composed of cm51a-type ultra-fine powder mill, qf5a-type turbine classifier, bag dust collector, collector and high-pressure fan

(I) CM51A ultra-fine mill

the structure of CM51A ultra-fine mill is shown in Figure 1. Materials less than 8 ~ 10mm are fed by the feed hopper through the double screw feeder. The feeding speed is automatically adjusted according to the actual load of the crusher, and the feeding particle size can be controlled. The two crushing chambers are arranged in line with each other. The diameter of the second chamber is slightly larger than that of the first chamber, and the middle is separated by an interchangeable circular retaining ring. The discharge port of the second crushing chamber is also equipped with a retaining ring with the same shape to be separated from the fan. Each crushing chamber is equipped with two rows of rotors. At the top of all rotors, replaceable hammers made of high hardness wear-resistant alloy steel are installed. Parallel to them is the high wear-resistant lining plate embedded in the inner side of the shell with special treatment, with a small gap between them. The materials move with the rotating air flow in the crushing chamber, and the particles impact, collide, rub and shear each other; At the same time, due to the centrifugal force of the rotating body, the particles are continuously crushed by the impact, friction and shear of the inner wall of the crushing chamber. The crushing chamber has the function of impact and airflow flutter crushing, and the most effective crushing interval occurs between the two rows of rotors in each crushing chamber. After entering the first crushing chamber, the material is crushed into powder with the size of hundreds of microns, while the linear speed of the rotor in the second crushing chamber is greater than that in the first chamber, and the powder passing through this section is more impacted and crushed. Due to the increase of the diameter of the second crushing chamber, the crushing time of the powder is prolonged, and the rotor of the crushing chamber also has the grading function. The fineness of the powder here reaches several microns. After two-stage crushing, the materials are sent to the air classifier by the fan for classification. The coarser particles that do not pass through the classifier will be returned to the crusher through the rotary discharger and then crushed. The hard to grind gravel and residual impurities in the materials can be automatically discharged out of the machine through the special slag discharge device in the machine. Through the fine particles of the classifier, they enter the micro powder collection system and become the final product

Figure 1 structural drawing of CM ultra-fine pulverizer

1 – base; 2 – slag discharge device; 3 – spindle; 4 – air inlet; 5 – feeder; 6 – hopper; 7 – one chamber rotor; 8 – one chamber retaining ring; 9 – lining plate; 10 – second chamber rotor; 11 – second chamber retaining ring; 12 – Fan

(II) qf5 turbine classifier (Figure 2 -)

qf5 turbine classifier separates coarse and fine particles by relying on the inertial centrifugal force generated by the rotor and the force of air flow on particles to achieve the purpose of classification. Its working principle is: the air flow containing solid working medium from the pulverizer or material dispersion equipment enters the classifier through the feed pipe 1 and mixes with the air flow introduced from the secondary air inlet 6 to the rotor area, as shown in Fig. 2. The rotor with blades rotates at a certain speed to make the air flow in this area rotate and form a centrifugal force field, so as to separate the coarse and fine materials. The coarse particles are discharged through the return pipe 7. The fine particles are carried out of the classifier by the air flow through the gap between the rotor blades to become classified products. The cross section of classifier rotor is shown in Figure 3. The rotor is equipped with several blades, with a certain forward inclination in the radial direction, and the upper and lower blade discs have different diameters. The rotation speed of qf5 turbine classifier is adjustable and can be selected according to different materials and product fineness requirements

Figure 2 working principle diagram of QF turbine classifier

1 – feed pipe; 2 – rotor; 3 – shell; 4 – transmission parts; 5 – air outlet pipe; 6 – secondary air duct; 7 – return pipe

Fig. 3 rotor section

(III) process flow

process flow of CXF impact ultrafine crushing system, as shown in Fig. 4. It is composed of CM ultra-fine powder mill, QF turbine classifier, micro powder collector, tail fan and electric control cabinet. The material (≤ 10mm) enters the superfine crusher 1 from the hopper through the double screw feeder. The feeding speed is automatically adjusted according to the actual load of the crusher and the feeding particle size is controlled. The materials in the pulverizer are crushed by high-speed rotating hammer impact, grinding, shearing and mutual collision between materials. The crushed material enters the turbine classifier 2 with the air flow, and the classification point of the classifier is adjusted according to the particle size as required. After classification, the ultra-fine powder enters the collector 3 for collection, and the coarse particle returns to the pulverizer for regrinding (closed-circuit system) through outlet 5, or is collected as product 2 (open-circuit system). The tail air enters the dust collector for purification and is discharged by the fan. The total weight of the whole set of system equipment is about 14 T, the total installed capacity is 92 kW, and the total floor area is nearly 90 M2 (15 m) × 6 m) and the maximum installation height is about 8.0 M. the whole system works under negative pressure without dust hazard

Figure 4 process flow of CXF impact ultra-fine pulverizing system

III. application

CM51 impact ultra-fine pulverizer and qf5 turbine classifier were successfully developed by Xianyang non me
tallic mine research and Design Institute in 1993 on the basis of undertaking national key scientific and technological projects, filling a number of gaps in China. After several years of continuous improvement and renewal, its performance index has exceeded the level of imported equipment in some aspects. It has been finalized as CM51A ultra-fine pulverizer and qf5a air classifier, which are widely used in the ultra-fine pulverization production of various functional non-metallic mineral materials and other materials. Some applications of ultra-fine grinding are introduced below

(I) application of ultra-fine grinding of coal series kaolin minerals

the ultra-fine products of coal series kaolin in China are divided into calcined soil and non calcined soil according to whiteness; It is divided into filler grade (- 10) according to particle size μ m) Product and coating grade (- 2) μ m) Products. Among them, the production process and equipment for processing filler grade coal series calcined kaolin products recommended by many domestic materials are usually: raw ore – coarse crushing – ultra-fine crushing, classification (Xianyang grinding) – calcination – depolymerization, dispersion – product packaging. Among them, Xianyang mill refers to the CM51A ultra-fine mill and qf5a air classifier produced by the powder center of Xianyang research and Design Institute of non metallic minerals. It obtains – 10 after the raw ore less than 10mm is ultra-fine crushed by CM51A ultra-fine mill and graded by qf5a air classifier μ M calcined raw materials with a passing rate ≥ 90%. The technical equipment has been widely used in ultra-fine deep processing products of coal measure and non coal measure kaolin in Wuhai, Inner Mongolia, Shizuishan, Ningxia and Datong, Shanxi. The production practice results in some areas are shown in Table 1

Table 1 practice of ultra-fine comminution of coal measure kaolin in some areas

(II) application of ultra-fine comminution of calcite minerals

CXF series impact ultra-fine mill developed and produced by Xianyang nonmetallic mine research and Design Institute is suitable for ultra-fine comminution of calcite carbonate minerals, mainly used to produce 800 ~ 1500 mesh ultra-fine heavy calcium carbonate. Its products are now widely used in plastics Rubber, paper filler and other fields. The production practice in some areas is shown in Table 2

Table 2 practice of ultrafine grinding of heavy calcium carbonate in some areas

note: the product particle size test results are provided by the manufacturer

(III) application of ultra-fine comminution of wollastonite

CXF51A impact ultra-fine comminution and classification complete set of equipment is used for wollastonite processing. The output can reach 166.8 kg /h and the product particle size is (10 μ M (passing rate) reaches 100%, D50 = 2.66 μ m. Moreover, it can keep the wollastonite powder with high aspect ratio

(IV) ultra fine grinding of other mineral materials. The ultra-fine grinding process composed of

CM5 La ultra-fine crusher and qf5a air classifier has been used to study the ultra-fine grinding of other minerals, and good results have been achieved. The materials involved include talc, crystalline graphite, semi soft kaolin, illite, crushed mica, barite, brucite, zeolite Pyrophyllite, tremolite, muscovite, sericite, iron oxide red, coal, natural asphalt, p-phenylenediamine, etc. the production practice results of some materials are shown in Table 3

Table 3 production practice of ultra-fine crushing application of some materials

(V) CM51A ultra-fine crushing equipment can avoid product pollution in the crushing process

the ultra-fine crushing test production of 50 t secondary talc from a real estate in Shandong was carried out by using the process composed of CM51A ultra-fine crusher. When the Fe content of raw ore was 1.37%, after ultra-fine crushing, – 10 μ The Fe content in the product with a passing rate of 85.5% is 1.27%, and the Fe content in the slag discharge is 1.43%, indicating that some iron in the raw ore is discharged through the slag discharge device specially designed by the crusher, and the purity of talc has been improved after ultra-fine grinding. For ultra-fine grinding of high-purity graphite, such as high-carbon graphite of a factory in Inner Mongolia, the specification is lg100-96. The carbon grade is 96.28%, ash 3.08%, volatile 1.14% and moisture 0.57%. The ultra-fine comminuted products under the conditions of different classifier speeds are tested, and it can be seen that the passing rate of product – 500 mesh is 97.93% ~ 99.90%, and the Fe content is ≤ 100 × 10-6, carbon grade 96.88% ~ 97.68%, ash 1.67% ~ 2.05%, volatile 0.65% ~ 1.16%, moisture 0.3% ~ 0.6%. The results of this experimental research fully meet the requirements of foreign investors, and the products have been exported to Japan, South Korea, Switzerland and other countries in batch. It can be seen that after the high carbon graphite is crushed by CM51A ultra-fine pulverizer, the purity of the product has not changed significantly, but the fineness has become finer

(VI) CM51A ultra-fine grinding equipment can be used for material dispersion

CM51A ultra-fine powder mill also has the functions of depolymerization and dispersion. For light calcium carbonate, because light calcium carbonate is produced by chemical method, some conditions often change in the production process, resulting in incomplete carbonization of products, some particles are too large, and some ultrafine particles are agglomerated, resulting in the instability of the final product; For calcined kaolin, the product forms agglomeration after calcination, which affects its use effect. By improving the working parameters of CM51A ultra-fine pulverizer, the instability of light calcium products and the agglomeration of calcined kaolin ultra-fine powder are completely solved

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