Modeling of iron ore pelletization using 3**(k-p) factorial design of experiments and polynomial surface regression methodology

The process of size enlargement or agglomeration finds a variety of applications in material processing and utilization. Pelletization is one such process which uses water as medium and revolving units (Disc/Drums) to form spherical pellets from fine particulates. Green or wet pelletization is the first step in pelletization process and is of critical importance since the effectiveness of the subsequent stages of drying and in duration depends on the quality and quantity of green pellets. This research presents the work carried out to develop model equations to predict the size distribution of pellets at any given level of intervals. Modeling of pelletization was oriented towards predicting the size distribution of pellets at any given level of variables. The prediction of pellet size distribution involves quantification of the self preserving curve and correlation between D 50 and the variables. A new model has been developed to predict the size distribution of the pellets using advanced statistical software "STATISTICA". The equation Y=-0.3757X 2+1.6256X-0.74 where "Y" is the cumulative wt.% passing and "X" is D/D 50 was used to predict the pellet size distribution. Correlation between D 50 and variables was given by "D 50"=4.226+(3.106*M)-(0.544*M 2)+(2.044*I)-(0.644*I 2)+(0.2444*T)-(0.028*T 2)-(0.058*M*I)+(0.0917*I*T) using quadratic response surface methodology. The mean pellet diameter "D 50" observed versus predicted was compared. A polynomial regression equation was used to quantify the characteristic curve of iron ore slimes agglomeration process. This can be utilized to predict the complete agglomerate size distribution irrespective of the operating conditions and the size of the pelletizer if a relationship such as agglomerate median product size D 50, as a function of the operating conditions is made available

Recovering iron values from iron ore slimes using cationic and anionic collectors

Indian iron ore industry is one of the world’s largest and growing at a rapid pace. Approximately 15% of the plant input is discarded as slime into slime ponds. Slime dams are now considered as threat, due to lack of high grade ores and acute shortage of land. More over this slime also poses threat to the environment. In addition to the economic benefit from the utilization of the waste as a resource; it also minimizes the land requirement, surface degradation, groundwater pollution, and destruction of forests. Iron ore beneficiation plants in India gives in three products, coarse ore lumps, which are directly charged to blast furnace, the classifier fines with or without beneficiation are fed to sinter plants and the slime which contain high alumina and low Fe currently discarded as waste. Slimes are to be further beneficiated to produce concentrates low in alumina and silica. These slime which after pelletization can be used as burden for the blast furnace. In order to utilize iron ore slime an efficient gangue removal flotation process is indispensable. This research work presents the flotation route for the removal of gangue in the slime to a level which is acceptable for the blast furnace route production of iron. Research has been carried out effectively and efficiently to utilize iron ore slime from the slime ponds of Joda and Noamundi region, India. This research work presents the results on the application of flotation to obtain the hematite and goethite concentrate with low gangue content from iron ore slimes. Fine particle size, complex mineralogy and presence of locked particles make it impossible for direct production of hematite concentrate by froth flotation unless mineral surface specific collectors are used. With flotation of silicates by using cationic collector and starch as a depressant for iron ore, starch adsorption occurred on quartz particles covered by iron oxides and on minerals which contain, Fe (II), Fe (III), and Al ions in their structure. An entire flotation of mineral complex is possible if the collectors used are mineral surface specific. Flotation performance was optimized by carrying out design of experiments

Processing of high alumina iron ore slimes using classification and flotation

The generation of iron ore slimes in India is estimated to be 10-15% by weight of the total iron ore mined. The iron ore values are lost to the tune of 10-15 million tons per year. Moreover these slimes which are stored in slime ponds at mine site pose threat to the environment. Considering the present magnitude of the iron ore slimes generation annually, quantity of slime accumulated over the years, depletion of high grade ore reserves, acute shortage of land at mining lease areas and stringent government norms, these slimes can be considered as a national resource if properly beneficiated using innovative technology. These slimes are readily available in finer size typically assaying 55-60% Fe and 6-8% alumina eliminating the need for crushing to finer sizes. This paper presents the research work carried out to recover Fe values with low alumina and silica content from high alumina iron ore slimes of India, using combination of hydrocyclone and flotation. Fine particle size, complex mineralogy and presence of locked particles determine the impossibility of direct production of hematite concentrate by froth flotation. Classification of slimes with two stage hydrocyclone gives a concentrate containing 61.99% Fe, 4.0% Al 2O 3 and 3.22% SiO 2, with Fe recovery of 54.55% in Stage-I. Concentrate from Stage-II hydrocyclone contains 62.19% Fe, 3.45% Al 2O 3 and 2.79% SiO 2 with Fe recovery of 47.45% with respect to initial feed. Further the concentrate from Stage-II hydrocyclone is beneficiated using reverse cationic flotation by using amines and direct flotation with fatty acid. A final concentrate of 64.46% Fe, 2.66% Al 2O 3, and 2.05% SiO 2 with Fe recovery of 69.03% in flotation stage and 34.13% with respect to the initial feed was obtained with reverse cationic flotation. While conducting flotation of aluminosilicates by using amines as a collector and starch as a depressant for iron ore, starch adsorption occurred on aluminosilicate particles covered by iron oxides and on minerals which contains Al and Si ions in their structure; consequently an entire flotation of mineral complex is possible by controlling electrokinetic phenomenon