The analysis of chemical and mechanical parameters of colemanite flotation

Some chemical and mechanical parameters such as agitation intensity rpm, airflowrate cc/min, pulp solid concentration g/lt, energy input watt/cc are important parameters in flotation practice affecting grades and recoveries of concentrates.In the past E.Yigit carried out laboratory flotation tests on McArthur River ore of Northern Territories of Australia showing the importance of agitation intensity and air flowrate. In the present work the above parameters were tested on Colemanite ore of Bigadiç district of Turkey. Colemanite ore of Bigadiç district of Eti Mining consisted of Colemanite and Calcite+Clay minerals (Illite) and average assay values were below.31,67 % B2O3, 30,29 % CaO, 13,37 % free CaO, 4,0 % SiO2, 1,95 % MgO, 0,13 % Na2O and 0,10 FeO.The flotation tests were carried out at the pH of about 9,5 under the buffer effect of Colemanite. Under this pH of 9,5 the surfaces of Colemanite and Calcite minerals are + signed. Therefore to choose an anionic collector sensitive only to Colemanite minerals was first step.In the flotation tests using sulphanate collectors with 1 lt and 2 lt cells ,with 200 g/lt and 100 g/lt pulp solid concentrations and at 1000, 1200, 1400 agitation intensities Calcite minerals were floated prefentially against Colemanite minerals In the flotation tests using Succinamate with 1 lt cells, 200 g/lt solid concentration Calcite minerals were floated again against Colemanite minerals. In the flotation tests using Succinamate with 2 lt cells, 100 g/lt solid concentration Colemanite minerals floated againts Calcite minerals contrary to expectations.After completion of many flotation tests it was found that a Sulphanate and Succinamate mixture was selective for Colemanite minerals against Calcite minerals. Thereafter flotation tests were carried out using this collector mixture Feed material consisted of Colemanite ore after desliming namely discarding of -10 micron particles and with about 30 % weight loss.The results obtained using different agitation intensities and air flowrates and pulp solid concentrations with 2 and 4 lt cells are given below.There are critical upper and lower limits of agitation intensities and air flowrates for Colemanite minerals flotations at optimum conditions.The flotation tests with 2 lt cells separation of Colemanite and Calcite + Clay minerals were succesful. The highest grade of Colemanite Concentrate of 44,61 % B2O3 was obtained at 1000 rpm agitation intensity and 1000 cc/min air flowrate. After the increase agitation intensity to 1200 rpm the slight decrease of Colemanite concentrate grade to 42,69 % B2O3 was evident but separation index was increased from 34,07 to 36,78.At higher agitation intensities and air flowrates grades of Colemanıte concentrates and separation indexes were decreased. This phenomena indicates the presence of critical agitation intensities and air flowrate limits. Exceeding these limits (Colemanite minerals) the selectivity of against Calcite minerals in the flotation with present collector mixture decreases.In the flotation tests with 4 lt cells separation of Colemanite minerals from Calcite+Clay minerals were more succesful In these tests not only presence of upper critical intensity but the presense of lower critical intensity were apparent.The flotation tests at 1000 rpm agitation intensity and 1000 cc/min air flowrate after reagent additions and conditioning were not succesful. But increasing agitation intensity to 1200 rpm keeping all the other condition same resulted in a succesful flotationThe best results of 4 lt cell flotation tests were obtained at 1200 rpm agitation intensity and 1000 cc/min air flowrate as 44,15 % B2O3 Colemanite concentrate grade and 37,33 separation index were obtained.Here also also critical upper limits of agitation intensities and air flowrates are present. Exceeding these limits the drops in grades and separation index are inevitable.Best results with this collector mixture were obtained at 1200 rpm agitation intensity, 1000 cc/min air flowrate and 50 g/lt pulp solid concentration. At above conditions it is possible to produce Colemanite concentrates of 45 % B2O3 grade with 60-70 % recovery after desliming of 10 micron material with 30 % material loss.Keywords: Colemanite, flotation, chemical, mechanical, parametre, mixture, airflowrate, seperation index, pulp