Case

grinding mills ratio

2019-08-20T20:08:23+00:00 Estimated Reading Time: 11 minsNew content will be added above the current area of focus upon selection

In spite of a great number of studies in the field of fracture schemes there is no formula known which connects the technical grinding work with grinding results. To calculate the needed grinding work against the grain size changing three semi-empirical models are used. These can be related to the Hukki relationship between particle size and the energy required to break the particles. In stirred mills, the Hukki relationship does not apply and instead, experimentation has to be performed to determine any relationship. • Kick for d > 50 mm$${\displaystyle W_{K}=c_{k}(\ln(d_{A})-\ln(d_{E}))\,}$$• Bond for 50 mm > d > 0.05 mm$${\displaystyle W_{B}=c_{B}\left({\frac {1}{{\sqrt {d}}_{E}}}-{\frac {1}{{\sqrt {d}}_{A}}}\right)\,}$$• Von Rittinger for d < 0.05 mm$${\displaystyle W_{R}=c_{R}\left({\frac {1}{d_{E}}}-{\frac {1}{d_{A}}}\right)\,}$$with W as grinding work in kJ/kg, c as grinding coefficient, dA as grain size of the source material and dE as grain size of the ground material. A reliable value for the grain sizes dA and dE is d80. This value signifies that 80% (mass) of the solid matter has a smaller grain size. The Bond's grinding coefficient for different materials can be found in various literature. To calculate the KICK's and Rittinger's coefficients following formulas can be used $${\displaystyle c_{K}=1.151c_{B}(d_{BU})^{-0.5}\,}$$ $${\displaystyle c_{R}=0.5c_{B}(d_{BL})^{0.5}\,}$$ with the limits of Bond's range: upper dBU = 50 mm and lower dBL = 0.05 mm.