A Comparative Study Of The "Releaseanalysis" Froth Flotation Test

Evaluating and analyzing separation efficiency of each unit operation or thewhole production system are the main task of the technology management and alsothe primary means to improve economic efficiency and competitiveness in coalpreparation plants. To evaluate the separation efficiency of a conventional flotationsystem, Operators and researchers in coal preparation plants are trying to find anexperiment method which is similar with the "float-sink test" in the gravity separationthat can be used to draw the “standard clean coal yield curve of flotation”. In1953，C.C.Dell proposed a technique known as the "Release Analysis”, that is, tocharacteristic coal flotation performance by carrying out flotation experiments in alaboratory flotation machine, a few different products can be get to. Then, the"Release Analysis” spread worldwide and generated several variants, including ISO8858-2(froth flotation test-Sequential Evaluation) and ISO8858-3(froth flotation test-Release Evaluation) and MT/T144-1997(methods for the coal flotation test byProgressive Release) of the coal industry standard in China.In this paper, theoretical comparison and analysis of the three "Release Analysis"froth flotation tests were carried out. Coal sample is separated into two parts i.e.“unfloatable” and “floatable” in Release Evaluation flotation test method by adoptingthe floatation procedure of one roughing and several scavenging, then severalproducts of different qualities are gotten by cooperatively controlling the aeration rateand flotation time of the “floatable” part. This Release Evaluation flotation testprocess is simple and has fewer batches, but multistage reagent addition method has acertain influence on flotation selectivity. Meanwhile, the regulation of aeration rate inflotation has a larger effect on the stability of the flotation process. SequentialEvaluation flotation test method divides coal into several groups of different productsby combining “tailings scavenging” and “concentration”，which has the advantages offewer flotation batches, more products，lower ash and yield concentrate. On the otherhand, the product of the previous flotation test is used as test material in eachsubsequent test of the Sequential Evaluation, so the subsequent test is stronglyinfluenced by the previous flotation test results. Progressive Release flotation testmethod gets the best flotation operation conditions through a multiple factors andmultiple levels of orthogonal test firstly, and then one concentrate product and severalgangue products are obtained through “concentration” and several times of “tailings scavenging”. It’s highly selective, but it has more flotation batches and less products.An experiment study was conducted out to compare the selectivity of the three"Release Analysis" froth flotation test methods, the results indicate that the shape ofthe ash-yield curves obtained by these "Release Analysis" froth flotation tests aresimilar. The scope of the ash-yield curves obtained by both Progressive Release andSequential Evaluation flotation test is wider than Release Evaluation flotation testwhich has a higher start point of ash. Both Progressive Release and SequentialEvaluation flotation test are highly selective, in addition，Sequential Evaluationflotation test is more sensitive to the change of the coal surface properties.An experiment study was conducted to certify the repeatability of the three"Release Analysis" froth flotation test methods, the experimental results show thatProgressive Release flotation test method has the best repeatability, followed byRelease Evaluation flotation test method; the Sequential Evaluation flotation testmethod has the worst repeatability among the three. For the subsequent test which hasthe largest production number is influenced by the previous flotation test result. Fromthe whole viewpoint, the quantity and quality differences among the same productfrom repeated experiments of three methods have a slight effect on the ash-yieldcurves which illustrate that the three "Release Analysis" froth flotation test methodsare well repeatability.After the theoretical&experimental studies of the three "Release Analysis" frothflotation test methods, the conclusion is that the Sequential Evaluation flotation test isthe best method of the three test methods which has a higher repeatability than theothers and well selectivity. Then an experiment study on the type of collector used fordifferent coal samples is carried out to evaluate the applicability of the SequentialEvaluation flotation test, the results show that the Sequential Evaluation flotation testis sensitive in collector type while collector dosage is not，but it not means the amountof added collector agent is random, and n-dodecanoic collector is an ideal collectorfor the Sequential Evaluation flotation test.Coal flotation performance can be characterized by the Sequential Evaluationflotation test to evaluate a unit operation or the whole flotation system.