Study On The Hygroscopicity And The Transport Stability Of Lead Concentrate

The KIVCET lead smelting method is a new direct lead smelting technology. As the initial stage of the KIVCET lead smelting system, keeping the dryness of lead concentrate and its transport stability in the preparation part is important guarantee for the lead smelting process.In this paper, the transport and storage of bulk material conveying system was researched.It provides a theoretical basis for the realization of stable transmission and ensuring continuous production in the preparation stage.According to the transportation environment of the raw material, the experimental equipment was built. The humidity absorption of four groups of different particle size of lead concentrate material under1mm was researched. The experimental results show that the range of humidity absorption percentage of lead concentrate is between0.045%and0.717%. The humidity absorption percentage reaches the upper level0.717%for lead concentrate with diameter less than0.075mm under20℃and95%relative humidity. The hygroscopicity of dry lead concentrate changes mostly at the beginning5h and reaches balance after24h. The Critical Relative Humidity of lead concentrate material is between55%and58%,which decreases with the temperature increasing and grain size decreasing.The matching relationship about the feeding quantity, the belt speed, the width of material buildup and the change range of belt speed allowed under different particle diameter in experimental KIVCET lead smelting delivery system platform was studied with the control variable method. The experimental results show that the width of material buildup B, the dynamic accumulation coefficient α and dynamic accumulation angle β decreased in nonlinear proportional with the belt speed increased. The critical speed for scattering on the belt of lead concentrate material is maximum, which is0.219m/s under0.425-0.85mm in mass flow rate of30t/h, also the critical speed that does not appear spreading is respectively0.178m/s and0.139m/s under0.212-0.425mm and the size under1mm with the same mass flow rate.Based on the particle discrete element software, the influence rule of the outlet size of silo, the insert structure was studied. The results show that the unloading process can be divided into two periods, the initial acceleration and the stability flow period when the mass flow rate continually decreases with the level decreasing. The particle flow pattern tends to bulk flow in silo with the outlet size increasing. With the material depth increasing, the wall stress of the vertical silo increases gradually and the wall stress below silo cone decreasing continuously. The maximum value appeares in the junction between vertical section and cone bin. With the insert structure, the sticky area can be eliminated effectively, which can avoid to generate arching at the outlet of silo and improve the flow condition.