Research theory of microwave drying scheelite concentrate
Henan Microwave Equipment Network: This paper carried out the microwave drying process and microwave drying theory research with the typical metallurgical mineral particles of white tungsten concentrate. At present, most of the industry uses hot air, gas, steam (superheated steam), electric heating and other means to heat, the temperature gradient between the heat source and the material is the original driving force of energy transfer, the heat transfer method from the surface and inside When removing moisture, it is necessary to heat all the materials; and the driving force of mass transfer is the gradient of the water concentration between the inside and the surface of the material. The evaporation of moisture starts from the surface of the material, and the internal moisture gradually diffuses from the inside to the surface. Increasing the drying rate requires a higher external temperature to form a temperature gradient. (1) A new process for microwave drying of scheelite concentrate was studied. (2) The microwave drying kinetics of scheelite concentrate was studied. (3) Through the research of the experimental results and the theoretical analysis, the conclusion that the microwave drying characteristics are different from the traditional drying process is obtained. Medical Consumables and Accessories
medical consumables and accessories
1. Made from 100% cotton absorbent gauze. Folded edges or Unfolded edges. 2. White, dyed green, green, dark blue color are available. 3. Yarn usually is 40S, but 32S is also available 4. Mesh can be 12x8, 18x11, 19x15, 20x12, 24x20, 26x18, 30x20, etc. 5. The sizes can be 5x5cm, 7.5x7.5cm, 10x10cm, 10x20cm, 20x20cm, etc. 6. It can be 8ply, 12ply, 16ply, 32ply, etc. 7. Sterile or Non sterile. Steriled by EO or Gamma. 8. With X-ray detectable or without 9. High soft, absorbency, poison free and could do isolating or absorbing, washing protecting function in surgical operation. strictly confirming to BP,EUP, USP. 10. Passed CE Certificate, ISO 13485, etc. 11. For disposable use before sterilization and its expiry time is 5 years.
Medical Gauze,Medical Consumables,Medical Accessories,Medical Gauze Roll Jiangsu Asbao Medical Technology Co., Ltd. , https://www.iigloves.com
On the basis of the single factor experiment, the mathematical model of each factor and response value is established: dehydration rate=67.83-19.36x1+15.03x2+18.47x3-3.6xlx2-1.28x1x3+5.5x2x3-7.05x12-15.98 X22-10.06x32 was applied to optimize the process conditions of microwave-dried scheelite concentrate by response surface methodology. The results show that the order of microwave time, material amount and layer thickness on the drying of anthracite is the microwave time>>material The amount of material layer thickness; the influence of microwave time, material amount and material layer thickness on the dehydration rate is not a simple linear relationship. The primary and secondary terms have significant effects on the dehydration rate, and the interaction term has little effect. The response surface method is optimized for the microwave drying of titanium concentrate. The microwave process time is 174s, the material amount is 135g, and the material layer temperature is 92°C. The actual result of the relative dehydration rate at this time was 82.4%. At this time, the deviation between the experimental value and the prediction was 0.03%.
Through the characterization of the drying rate curve, the drying process can be divided into three stages: accelerated drying, constant-speed drying, and reduced-speed drying. The effect of the intensity of the microwave power on the drying rate is significant. As the microwave power increases, the drying rate of the material increases significantly, and the corresponding microwave drying time required is shorter. Through a series of analysis on the results of microwave drying of thin layer materials, it is determined that the Page model is suitable for describing and fitting the microwave drying process of scheelite concentrate, so this model can be used for scheelite under various conditions. The drying time of the mineral material is predicted.
Among them, microwave drying is characterized by the fact that the polar molecules inside the material rapidly oscillate in the microwave field to generate heat, which causes a huge internal vapor pressure gradient from inside to outside, which promotes the diffusion of moisture to achieve the purpose of drying. Aiming at the whole process of microwave drying scheelite concentrate, the water content change law of wet minerals was treated by concentrated wet volume method, and a mathematical model was established. According to the model, the water content change at different moments in the mineral was calculated, and the experimental data and calculation were carried out. Results The comparison analysis showed that the above model can better reflect the drying law of scheelite concentrate.
Microwave heating has the advantages of internal heating and selective heating. Since the dielectric constant ε' of water molecules is as high as 70-78, which is much larger than that of common minerals and compounds, in the microwave drying process, water molecules always preferentially absorb a large amount of microwaves, forming a large vapor pressure in a short time, and quickly escaping materials. The surface significantly reduces the drying time. This drying method reduces the overall heating of the material and greatly reduces the energy consumption. At the same time, due to the internal heating characteristics, a temperature gradient from the inside to the outside is formed in the material, and the direction is the same as the reverse of the water transmission. The process of mass transfer of water molecules is promoted and the drying efficiency is improved. Therefore, the microwave drying process is increasingly valued and rapidly developed. 