Application And Mechanisms Of Phosphorus-Reduction Collector In Reverse Flotation Of High-phosphorus Iron Ore

Along with the high speed development of modern industry, the limited rich iron ore and easy-to-recover iron ore resources were reduced rapidly, it is essential to carry out a beneficiation study on complex ultrafine iron ore with high content of impurities (phosphoric, sulfur). There are massive high-phosphorus iron mine worldwide, and the high-phosphorus iron mine accounts for14.86%of the total iron mine in China, namely,7.45billion tons. Ore-dressing study to reduce phosphorus content was carried out in domestic universities and institutes, but it remains a puzzle in beneficiation of high-phosphorus iron ore to reduce phosphorus content in iron concentrate and increase iron recovery. In this study, after a thorough analysis and investigation on flotation reagent, a high effective collector which is fit the iron property was designed and selected to reduce phosphorus in a reverse flotation, then, after optimizing reagent system and strengthen the matching and combining of reagents, the goal to increase recovery, reduce phosphorus content in iron concentrate and reduce ore-dressing cost can be attained.Firstly, the design of flotation reagent was conducted, using quantum chemistry method. Combining analysis of surface electric properties and infrared spectra and bench tests, the main minerals in high-phosphorus iron ore, the commonly used flotation reagents and the interaction between mineral surface and reagents were systematically studied. Regarding performances such as the selectivity, an effective and practical collector, RFP-138, was developed. The practical application of RFP-138in the beneficiation of high-phosphorus iron ore or even oolitic high-phosphorus hematite was actualized. The main results are as follows:1. Synthesis of RFP-138Based on collectors used in domestic and foreign phosphorus ore, a new type of phosphorus reduction reagent, SNA, was selected through molecular design. After condition test on synthesizing parameters, the fractional distillation and depuration parameters, and the carbon chain length were determined. After introduction of some other effective components,blended with self-developed YS04synergists, a new type of reverse flotation collector, RFP-138was prepared.2. Improvement of flotation performance of carboxylic acid collectorFloatation tests indicate that both modification of reagents and combined usage of them can improve the flotation performance of carboxylic acid collector. Higher recovery can be expected with reagents obtained from sulfonation modification, although there is still a shortcoming as it is as well necessary to use large amount reagent when modified carboxylic acid was used. Non-ionic surfactant with polyethylene oxide functional group may strengthen the flotation efficiency for a bulk with low dosage of SNA, and a small dosage of which may improve significant the recovery, with which, collophane and hematite can be effectively separated.3. Main composition of minerals and their reaction with collectorsBench test, zeta-potential measurement, and IR analysis were used to study the main composition of minerals in collophane and their reaction with collectors. The result indicate that the anion collector has obvious chemisorption on mineral surface, and the hydrogen bonding exists in this process, and a shift of characteristic absorption of chemisorption can be observed; meanwhile, according to the simulation of collector molecule using Gauss software bital theory quantum chemistry method, oxygen atoms on anion collector adsorbed first owing to the chemical reaction with calcium atoms, but they do not react with the phosphoric acid radical on cleavage plane of collophane, and they cannot react with hematite surface; Oxygen atoms of collector may form hydrogen bonding with hydrogen atoms on mineral surface,which tallies basically with the experimental study result. It is required to adopt appropriate pH so as to realize the separation of collophane from hematite through the reagents along with the inhibitors.4. Flotation performance and action mechanism of combined collectorIn artificial ore tests, better phosphorus-reduction effect can be obtained using the combined collector than oleic acid, while the Fe grade in the concentrate can be guaranteed; According to surface tension test, infrared spectra of minerals before and after the reaction with the collector, a preliminary discussion on the action mechanism of the combined collector was carried out.5. Study on the relationship of collector structure and its performanceFlotation tests were carried out to investigate the influence of the structure of non-polar groups on the activity of polar groups, the hydrophobicity of collector and the flotation capacity. Through inspected the collector base structure to the single mineral’s direct flotation experiment to the polar group response activeness, the collector sparse hydro energy strength and the flotation process performance influence, finally demonstrated:When collector exists in the form of molecular, the activity order for chemical reaction is:alkyl carboxylic acid> alkyl fatty acid> alkyl phosphoric acid> alkyl sulfonic acid> alkyl sulfuric acid; When the collector transfer to be a form of ions, the activity order for chemical reaction becomes:alkyl hydroxamic acid> alkyl carboxylic acid> alkyl phosphoric acid, alkyl carboxylic acid> alkyl sulfonic acid> alkyl sulfuric acid. Meanwhile, The calculation of the activity of polar group on anionic collector when using all slightly differential algorithms in quantum chemistry software, Gaussian09, shows that, besides providing the essential hydrophobicity, the activity of polar groups was influenced by the type and length of carbon chain of non-polar groups, although the capacity of collector remains unaffected. The activity of carboxylate ions can be improved gradually along with the increase of the unsaturation degree, and its dissolve and dispersion capacity in water increases as well, therefore, there existene of carbon ring in non-polar group is the main reason which contributes to the excellent collecting performance of RFP-138.6. Actual performance of RFP-138in real ore beneficiationBench tests on real ore indicate that the new phosphorus-reduction collector for iron ore, RFP-138, possesses excellent capacity for reverse flotation of phosphorus ore, and it can reduced the phosphorus content to a degree of a qualified concentrate, while ensuring the recovery of iron concentrate.The iron concentrate with above60%of iron grade,0.17% of phosphorus content and above80%of recovery can be obtained through closed-circuit test. The development of the new collector provides a new way of thinking for the effective phosphorus reduction with high-phosphorus iron ore.