Development and application of composite binder for iron-bearing dust pellets molding
The treatment of iron-bearing dusts and sludges by the rotary hearth furnace process has the advantage of sufficient utilization of valuable metals and a high impurity removal rate,and becomes one of the development trends of iron-bearing dust sludge treatment technology.However,the poor balling performance of iron-bearing dust sludge leads to low strength and easy pulverization of the pellets,which seriously restricts the environmental and ef-ficient production of the rotary hearth furnace process.An important means of improving the performance of raw materials and increasing the yield and quality of pelletized ore is the use of excellent binder.The composite binder was prepared by matching organic binder and bentonite,and the effect of composite binder on the cold performance and reduction performance of pellets was investigated.It was shown that the composite binder pellets exhibited ex-cellent green pellets performance.The drop strength and compressive strength of green pellets in the CB2-3 group(3％bentonite+0.5％binder B)reached 8.5 times/0.5 m and 78 N/P,respectively.It is because the organic bind-er has rich oxygen-containing groups,such as—OH,—COO—,etc.,which improves the hydrophilicity of the sur-face of the iron-bearing dust sludge and strengthens the connection between the bentonite and the iron-bearing dust sludge concentrate particles.The binder C forms a mesh structure during the drying process,which promotes the proximity of dust particles to each other,and was the main factor in the dry-ball strength enhancement of the CB3 group(3％bentonite+2％binder C).Meanwhile,the reduction of iron oxides and zinc oxides was more fully due to the increase in the content of organic components.The main reason is the pyrolysis of organic components at high temperature,which accelerates the pyrolysis of solid fuels and the diffusion of reduction products.However,exces-sive pore generation will lead to a decrease in the strength of the pellets.Industrial tests shown that compared with the composite binder YG-1 used in the field,the addition of CB2-3 and CB3 can significantly improve the production quality index of the iron-bearing dust pellets,while the cost of the binder decreased from 140 yuan/t to 115 yuan/t and 120 yuan/t,respectively,which achieves the effect of quality improvement and costs reduction.
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