Study On The Quality Improvement Of Magnetic Iron Concentrate

Along with magnetite resource of high quality dwindling, development and utilization of fine disseminated and complex iron ore becomes increasingly important, and only magnetic separation process has been difficult to adapt to the deteriorating nature of the ore, which has forced plants to select reasonable process to produce high-quality iron concentrate. Compared to gravity concentration and magnetic separation process, flotation can effectively remove the iron ore containing silicon from iron concentrate, reducing harmful impurities of the concentrate in the form of fine dissemination.Anhui iron processing plant adopts stage grinding- fine screen classification-middling regrinding process with second and third period magnetic concentrate grade of about 56% and 64%, with the nature of the ore constantly changing, concentrate grade fluctuating, sometimes concentrate grade only reaches 62%. Accompanied with the requirement of high-quality iron ore of steel mills and the falling prices of the concentrate resulting in the plant’s poor benefit, the process has been difficult to meet the demand of the plant, which,thus, highlights the importance of concentrate’s quality improvement. In this paper, taking secondary period magnetic concentrate in Anhui as the research object, the quality improvement experiments were conducted combining with single mineral test.Through exploring the impact of pulp p H value and dosage of ether amine collector GE-609 and fatty amine collector with different carbon chain length on floatability of single mineral, magnetite and quartz, the collecting performance of GE-609 and fatty amine with different carbon chain length in flotation was compared. It was found that within low reagent concentration,collecting capacity of fatty amine collectors was decreased as the carbon chain length increased, compared with GE-609, dodecylamine has better collecting ability. Impact of starch on flotability of quartz and magnetite and different reverse flotation indicators according to different quartz size were researched, dodecylamine and GE-609 acting as collectors, the results showed that starch played a unconspicuous role in quartz flotation but had some inhibitory effect on magnetite,but this effect was not significant.At low reagent concentration, floatability of quartz decreased as the particle size increased,while at high reagent concentration,-0.154+0.1mm quartz had better flotability than that of 0.2+0.154 mm and-0.1+0.03 mm, and the recovery of-0.1+0.03 mm quartz was almost constant with the reagent concentration increasing.Experimental study in laboratory mainly included property analysis of samples, tests of flotation machine and tests of magnetic flotation column. Flotation of different size fractions indicated that-0.1mm grain size is better in flotation effect,and dodecylamine has better collecting ability,based on which, condition tests of flotation machine reagent system, flotation pulp density and exploration of flotation flowsheet were carried out,and then flotation flowsheet of flotation column was explored on the basis of flotation machine reagent system.It showed that both one roughing-two concentrating process with flotation machine and one roughing-one concentrating with flotation column clould get flotation concentrate grade with 67%.Classification-flotation-magnetic separation process was adopted to upgrade the secondary stage magnetic concentrate,grinding fineness and the magnetic field strength condition test of flotation froth and coarse particles on the screen which composed of grinding middlings were carried out. Resultis showed that classification-closed circuit of one roughing-one concentrating with flotation column-magnetic separation of regrinding middling quality improvement process obtained the most total concentrate yield and recovery, had a advantage of simplifying technological process and favourable index for fine grade mineral,therefore, and was chosen as the final quality improvement process with a good index of total concentrate yield 78.65%,grade 67.02% and recovery 94.07%.