| In the beneficiation process of scheelite, the flotation separation of scheelite andcalcium-containing gangue minerals, such as fluorite, calcite, has been a worldwide problemtroubling the beneficiation industry. The problem is mainly caused by the similarity of thesurface physicochemical properties of these calcium-containing minerals. On the basis ofprevious studies, this thesis conducted the research of single mineral flotation behavior and itsmechanism under three representative collectors respectively. And further the thesis made adepth exploration on the flotation kinetics of both single minerals and artificial mixed ores.Single mineral flotation studies show that the collecting ability of sodium oleate, GYRand benzohydroxamic acid on three calcium minerals were relatively well under suitable pHconditions without adding sodium silicate but shows poor selectivity except benzohydroxamicacid which shows some selectivity. And the three minerals also showed the same flotation lawconsistent with the flotation conditions, which confirmed the separation difficulties betweenscheelite and fluorite, calcite. After adding the same amount of sodium silicate, fluorite is themost likely to be inhibited and scheelite is the most difficult to be inhibited significantly.When the dosage of sodium silicate was375mg/L, the recoveries of scheelite, fluorite andcalcite were respectively72.33%,3.02%and23.05%, which indicates that the separation maybe easy.The mechanism research of minerals and beneficiation reagents indicates that the modeof action of sodium oleate on the three calcium-containing minerals is all chemisorptions orreaction and the reaction product is mainly calcium oleate. But if the same amount of sodiumsilicate was added before adding sodium oleate, the results for the three minerals weredifferent. Sodium silicate does not affect the reaction between scheelite and sodium oleate.Calcium oleate could also be tested on its surface. Conversely, sodium silicate intenselyaffected the surface of fluorite and calcite, which completely presented the reaction betweenminerals and sodium oleate. In addition, the reaction mechanism of GYR andbenzohydroxamic acid on scheelite was also studied. Results showed that the reactionmechanisms were also chemisorptions or reaction.Research of mineral flotation kinetics showed that of all the flotation kinetics process ofscheelite, calcite and fluorite under different conditions, the model2(one-level matrix distribution model) fits best. Without adding sodium silicate, the flotation rate constant orderof the three minerals under each optimum conditions was as follows:k flourite k calcite kscheelite; At this point, the best flotation kinetic models for each minerals areas follows:After adding sodium silicate, the flotation rate constant of scheelite declined slightly, butthat of fluorite and calcite declined obviously. The order becomes:k scheelite k calcite kflourite.For example, when the dosage of sodium silicate was300mg/L, the flotation rate constantsfor scheelite was largely bigger than calcite and fluorite which verified the results of singlemineral flotation. In this case, the flotation kinetic model for each minerals were as follows:In the formula, represents the accumulated recovery, t represents the accumulatedtime.The flotation separation kinetics research of artificial mixed ores indicated that of all thethree flotation kinetics processes of scheelite concentrate, the model3(Two-level kineticmodel) fits best. Good separation indicators were achieved of all the three composite sampletests. And the best indicator was achieved by sample1, which were composed by scheeliteand fluorite by the ratio of1:1. The order of separation indicator was: sample1, sample3,sample2. And the order of scheelite flotation rate constant was the same to that of theseparation indicator, which further verified the role of prediction and guidance of flotationrate constants on the flotation separation indicators. |
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