Experimental Study On Selective Flocculation Enhanced Coal Flotation Process

Flotation is one of the main methods to deal with the fine grade slime in coal preparation plant currently,however into clay degree is more and more serious,floating coal entrained fine mud easily,causing a increase of the ash of flotation coal,effecting quality of flotation concentrate seriously.Selective flocculation could change the surface properties of coal,make the coal and mineral impurities dispersed,and then use the appropriate selective flocculant to selective flocculate coal particles,but mineral impurities remaining dispersion state,and finally collect the floc through flatation.Thus,by selective flocculation-flotation methods to improve the effect of flotation of high ash fine mud coal is a very significant issue.Based on in-depth understanding of the Malan 8#the basic properties of the coal,coal flotation reagent system was potimized,the flotation was investigated by adding dispersant and selective flocculants,further dosing way,spindle speed,redispersion and reflocculated were potimizated,and the surface characteristic of coal are studied using contact angle analysis,surface tension analysis,laser particle size analysis methods and Zeta potential analysis,through mechanism research,the results are as follows:1.Through exploring dispersant optimum amount and concentration of sodium hexametaphosphate,tannic acid,sodium silicate,sodium fluoride and sodium hydroxide,it is found dispersant has significant anti-condensation and anti-coagulation,there is a different effect during the different disperant,their strength order:sodium hexametaphosphate>tannic acid>sodium silicate>sodium fluoride>sodium hydroxide.When sodium hexametaphosphate concentration of 5%,the amount of 1100g/t of dry slime,the best dispersion is obtained.2.Using single-factor test,sodium hexametaphosphate as dispersant,the different molecular weight of anionic,cationic,ionic and nonionic poly acry lamidi(PAM)respectively as selective flocculants to potimizate flotation effect,and comparing the test results of each type reagents under the best dosage,the suitable PAM of Maian 8#coal is obtained that is cationic flocculant,molecular weight of 12 million,the dosage of 30g/t dry coal slime.3.In a condition of cationic flocculant of molecular weight of 12 million,the dosage of 30g/t dry coal slime,change dosing way,spindle speed,and redispersion and reflocculation tests are investigated and it is found that potimum results are dosing way of 1min(dispersant)-1min(PAM)-1min(collector),spindle speed of 1800r/min;flotation clean coal yield increased by 3.68%,2min plant product ash content was reduced by 4.92%,the total plant combustible recovery increased by 9.59.After redispersed and reflocculate test of the clean coal of selective flocculation-flotation are carried through,it is found that coal ash is also greatly reduced despite the lower yield of clean coal,indicating this method could reduce plant ash effectively.4.Flotation concentrate indicators are poor if no adding dispersant or kerosene,indicating during selective flocculation,if shale and coal particles could not be effectively dispersed,it would seriously affect the selectivity of PAM and flotation effect,and PAM can not play a role of collector.5.The contact angle,surface tension,laser particle size and Zeta potential analysis can be shown:The contact angle of coal sample increases adding dispersion and flocculation,the surface tension decreases onrrespondingly,indicating enhanced coal hydrophobic,beneficial interaction between coal and gas bubbles in the flotation process;Firstly the fine coal increased after adding dispersant indicating that clay mineral adhere to the coal separated,then fine coal reduced after adding flocculants,the reason is due to the coal particles flocculate into a group;Adding dispersant can improve the dispersibility and reduce its flocculation property,resulting in a increase of the absolute value of the non-target minerals(argillaceous)?potential substantially,then after adding flocculant,the absolute value of target minerals(coal)?potential is lower than the non-target,the larger the gap,the better selective flocculant.