The Effect Of Grinding Aids On Mineral Comminution Characteristics And Their Mechanisms

Grinding is widely used in metallurgyical, chemical and cement industry et al., which the major problems of the current are high energy consumption and low efficiency. Gringing aids have been applied to improve the efficiency and reduce the energy consumption to some extent, however, the mechanism research about them have not been widely spread in the present. In this thesis, the ore properties of the bauxite and the magnetite ore were studied at first, then the change rules of mineral comminution characteristics were researched under the conditions of the natural state, the water immersion and the grinding aids solution immersion, respectively. Finally, the mechanisms of the grinding aids have been studied by measurements of FTIR, scanning electron microscope and energy dispersive X-ray spectroscopy et al.The bauxite used in this paper consists of diaspore, kaolinite and illite etc., which being composed of easily soluble and hydrolyzed minerals, and there exists many defects including microcracks, joints etc., a part of which are filled by crystals of low strength and cements, such as clay minerals. Mineral composition of the magnetite ore is relatively simple, which mainly are magnetite and quartz. Magnetite ore seldom contain defects of microcracks and micropores between crystalline grain due to the dense structure.Copmared with the bauxite at the natural state, the Bond ball mill work index of the bauxite soaked with water, Z-164D solution, Z-162C solution and sodium hexametaphosphate solution were decreased maximally by 1.05%,3.79%,3.28% and 4.80% respectively, and the uniaxial compressive strength dropped maximally by 26.86%,42.79%,43.52% and 45.21% respectively.Copmared with the magnetite ore at the natural state, the Bond ball mill work index and the uniaxial compressive strength of the magnetite ore soaked with water remain unchanged essentially, and the Bond ball mill work index of the magnetite ore soaked with calcium oxide emulsion, sodium silicate solution and sodium hexametaphosphate solution increased maximally by 14.44%,39.90% and 25.87% under the test conditions, and the uniaxial compressive strength still remain unchanged.The chemical adsorption between Z-164D, Z-162C, sodium hexametaphosphate and diaspore, kaolinite on the bautite surface were confirmed through the analysis of FTIR and energy dispersive X-ray spectroscopy, and then the thick hydration adsorbed layer appeared on the bautite surface. The process of water coming into bauxite, and the mechanical, physical and chemical reaction of the water could be accelerateed due to the ascending water content on the bautite surface, then the strength of the bauxite would decline further.The chemical adsorption between calcium oxide and quzrtz, sodium silicate and magnetite, quartz, sodium hexametaphosphate and magnetite on the magnetite ore surface were confirmed through the analysis of FTIR. Because the water could not dip into magnetite ore, the efffect of physical and chemical adsorption on the uniaxial compressive strength of the magnetite ore was very weak. Nevertheless, during the drying of Bond ball mill work index sample, a series of physical and chemical changes occurred on the magnetite ore surface, and new substances and hydraulicity gelatum would be created, which can fill and connect the cracks on the surface, therefore, the Bond ball mill work index of the magnetite ore soaked with calcium oxide emulsion, sodium silicate solution and sodium hexametaphosphate solution increased generally.The effect of the surface active substance on mineral strength and hardness is greatly influenced by the structure and the texture of the mineral.The regional environment on the mineral surface will change to a large extent because of the adsorption of surface active substances, which being of strong hygroscopicity. The process of water coming into mineral, and the mechanical, physical and chemical reaction of the water could be accelerateed due to the ascending water content on the mineral surface, then the strength and hardness will decline evidently.