At present, the drying of beneficiation products mainly uses machines such as rotary kilns, direct or indirect heating cylinder dryers, electric drying ovens, and far-infrared drying equipment. However, these equipment occupy a large area, consume a lot of energy in operation, and have low heat utilization rate. At the same time, the degree of automation of equipment operation is low, the loss of products during the drying process is large, and the drying cost is high, which seriously affects the economic benefits of the dressing plant. At present, the drying technology is developing rapidly, and the research and application range of spray drying, fluidized bed drying, and air flash drying have been very extensive.
Aiming at the characteristics of beneficiation products, combined with the new drying technology of other industries, a high-efficiency flash dryer suitable for mineral products has been developed on the basis of airflow drying, also known as rotary crushing airflow rapid drying equipment.
1. Working principle and system composition
The high-efficiency flash dryer is a kind of airflow drying equipment, and the drying medium is hot air. The working principle of the high-efficiency flash dryer is: the air enters the dryer after being heated in the heat exchanger by the blower, and the rotating hot air contacts the wet material falling from the feeder, so that the surface of the wet material is dried rapidly. The mechanical impact and the blowing action of the high-speed rotating hot air flow cause the materials to produce violent impact, shear and friction in the floating state, and the bonded materials are loosened and dried quickly.
The material is subjected to the axial thrust of the paddle and the tangential wind force of the rotating airflow, and the drying process is completed instantly (within a few seconds) in the dryer. The dried powder enters the cyclone separator and bag collector with the airflow, the finished product is discharged by the star unloader, and the tail gas is discharged by the induced draft fan.
Second, the characteristics of the equipment
1. Drying machine
Utilizing the principles of airflow drying and flash drying, the drying host is designed as an airflow flash composite dryer.
The stirring device of the main engine has five stirring series, and each series has three assembly forms. The test found that the type of rotary device suitable for mineral products is multi-blade and multi-layered. The volumetric heat transfer coefficient hv of the main engine is 75640kJ (h·m3·℃), and the thermal efficiency is high, which can reach more than 90%. At the same time, it solves the problem of mine blockage. The problem. The design range of the rotating speed of the stirring device is 300-1400rmin, and the transmission mechanism is simple and easy to maintain.
In order to meet the drying characteristics of various mineral products, two host types are designed: vertical (L type) and horizontal (W type). The L-type main engine has no classifier and has a small length-to-diameter ratio, which is suitable for mineral products with high dry density and fine particle size; the stirring blades of the W-type main engine are made of wear-resistant materials. Mineral products with coarse particle size. The W-type main engine solves the problem of excessive wind demand for vertical structures.
2. Collection system
Absorbing the technical advantages of the dry collection system (including cyclone separator and bag filter) in the chemical industry, a rotating back-blowing cylinder bag filter and a long cone cyclone separator suitable for single mineral product operations have been developed. The collection system has the following characteristics: the product collection rate can reach 85%-95% at the cyclone; the bag filter occupies a small area, the processing capacity per unit area is large, and the pressure loss is small, and the power of the induced draft fan equipped with the system is reduced to achieve energy saving. The purpose of reducing consumption; the bag of the bag filter is made of needle-punched filter cloth, which has the characteristics of heat resistance and good gas permeability, which can ensure that the material loss is below 0.1%, and the dust content of the exhaust gas is low, which meets the environmental protection requirements; Cyclone The combined use of the machine and the bag distributor makes the drying process of mineral products completely closed, with high product purity, high recovery rate, no pollution to the environment, and improved operating conditions.
3. Drying characteristics
A rotary dispersing device is installed in the convection dryer, and the hot air in the dryer rotates up, and the materials entering the dryer are fully dispersed in the dryer under the joint action of the rotating dispersing device and high-temperature hot air, and the specific surface area expands rapidly, which speeds up the transmission process. The speed of heat and mass transfer makes the material dry quickly. The dried material is entrained by the hot air of the moisture carrier and rotates.