Research On Mechanism And Technology Of Different Starches As Hematite Depressant

The flotation of refractory hematite has two methods, flotation and reverse-flotation which uses soap (sodium oleate) as anionic collector. Depressors mostly are organic compound which has hydroxy grope, Starch is a typical representative. Finding an effective, economy and environmental depressor of ferric oxide in reverse flotation is an important task. Hematite and pure quartz mineral are the research objects in this dissertation, influences of several reagents, especially depressants on reverse-flotation of single mineral have been investigated. The mechanism of reverse-flotation was analyzed through Zeta-potential experiment, adsorbance detection and other methods. Crystal surface properties were calculated and optimized through MS software, and we conduct dynamics simulation between depressant and mineral crystal surface to know the action effect, and all the results simply calculated. The results were applied to actual mineral separation of refractory oolitic hematite. Main conclusions are as follows:(1) Single mineral tests:the collecting ability of HY is better than sodium oleate, the recovery reaches more than80%when pH=11; the recovery rate of quartz increases significantly with the increasing dosage of activator, but influence little on hematite; the order of depression to iron shows:causticizing corn starch> causticizing phosphate starch> causticizing carboxymethyl starch> ordinary starch, but depression effect to gangue mineral is not obvious, quartz is in the state of suspension which will be good for reverse-flotation and desiliconization of iron ore.(2) Zeta-potential experiment indicates that ordinary starch and causticizing corn starch have the best selective depression ability when pH=10-12.5, The effect of causticizing corn starch to hematite is better than ordinary starch, but it don’t work on quartz which indicates the difference starch on two kinds of mineral will be benefit to the reverse-flotation tests.(3) The adsorbance results indicate that causticizing corn starch adsorb on the surfaces of hematite and quartz when pH=10.0, but the adsorption on hematite is more easily, the adsorption effect of quartz is relatively poor.(4) Dynamics simulation of depressant on the mineral surface shows that adsorption of modified corn starch on hematite is more easily, the original and final hydrogen bond adsorptions are obviously different between hematite and quartz which mainly results the inhibition effect of modified corn starch to iron in the reverse-flotation tests. This result is identical with the reverse-flotation tests.(5) Actual ore tests indicate that all the ore used belong to acid refractory oolitic hematite which consist high quality of phosphorus, the main ore outputs hematite and the gangue mineral is mainly quartz. The tests adopt stage grinding,3min of grinding followed by30min free settling, the suspension is used as concentrate and the spare pulp continues to grinding5min for reverse-flotation. The optimum condition is as follows:600g/t dosage of causticizing corn starch, activator CaO dosage is1000g/t, HY dosage is600g/t. What’s more, causticizing corn starch has the best inhibition effect to iron among these kinds of starch. The iron concentrate more than56percent, the concentrate with0.27percent phosphorus and36.53percent of tailing grade can obtain from closed-circuit test process whose results have certain disparities from industrial technology index. Further perfection, optimization and improvement are needed. But these results have a certain instruction to reverse-flotation of this kind of refractory hematite.The dissertation was supported by"Frontier Research Project of Central South University"(2010QZZD002).