Development of Mathematical Model for Integrated Iron Ore Grinding Ball Mill-air Classifier Circuit: Energy-grind Optimization

Nerune, Virendra Prakash (2016) Development of Mathematical Model for Integrated Iron Ore Grinding Ball Mill-air Classifier Circuit: Energy-grind Optimization. Masters thesis, Indian Institute of Technology Hyderabad.

Text
CH14MTECH11010.pdf - Submitted Version
Restricted to Registered users only until 2 August 2019.
Download (4MB) | Request a copy

Abstract

Exponential increase in the demand of steel all over the world is leading to rapid depletion of the high grade lump iron ore, leaving the low grade iron ore as fines. Hence industries are forced to use low grade iron ore fines by beneficiating it which produces desired high quality ore required for blast furnace. The fines are subjected to the communition like crushers and mills as the alternative beneficiation techniques for uniform liberation of iron ores which can be used as a feed for blast furnace. In current industries, this liberation technique consumes high energy and lack of constant liberation of the iron fractions. In this study, we have used JKSimMet tool for mass balancing, model fitting and simulating the closed circuit pelletization plant, Tata steel Jamshedpur. The inputs to the circuit like plant operating and design data’s, particle size distribution (PSD), flow rates (TPH), bond work Index, etc were determined by collecting each sample from site and analysing it in laboratory. The ball mill used in simulation is assumed to be working at steady state which utilises perfectly mixing model. The overall mass balancing is achieved with a consistency as compared to the plant data followed to which the model fitting were accomplished. Further, simulations were conducted to monitor the effect of change in ball size distribution on the PSD. As plant ball mill is consuming more energy and unable to maintain the constant optimum ground product, it very important to go for parametric study of plant mill and verifying the effects of the ball mill operating conditions on the performance of the ball mill as well as ROKSH air classifier. The optimum conditions were estimated by minimizing the energy requirement to ball mill and the optimum ground which was the requirement of pelletization plant. This involved a large set of parametric simulations of grinding and classification circuit using JK SimMet involving 5 levels of variation in fractional critical speed of the mill , flowrate of the feed, load fraction in the mill, rotor speed of the classifier, analysis of effect of ball size distribution on ball mill discharge. A methodology used to build a simple comminution and classification circuit simulator using the population balance model framework is discussed in this paper. Models from literature which include Whiten(1972)’s cone perfectly mixed Ball mill models. Moreover, a batch grinding mill model is developed for determination of so called breakage rates and appearance functions by back calculation method which is based on Austin’s approach. The results showed that it is possible to use custom made simulators to predict performance of simple comminution circuits. An attempt will be made in future to extend the work to more complex circuits.

[error in script]

IITH Creators: