In this paper, the flotation method has been used for the preparation and beneficiation of coal samples. The Plackett-Burman methodology has been applied to design of experiments and this experimental design method is based on Hadamard matrix and ash content and efficiency index have been considered as responses. The operating conditions were chosen based on some screening tests. Results showed that ash content and efficiency index could be 15.2% and 42.55 respectively when the values of collector, frother and solid percent were 5.29 kg/t, 78 g/t and 10% respectively. The effects of variables were studied by which increasing and decreasing of responses could be transparently observed. Coal flotation kinetic was studied and the results show that the optimum time is 2 min to complete the flotation process. In this investigation, the coal flotation procedure was optimized and the time of flotation has been found by which energy consumption would be significantly reduced. Also, coal qualities could be improved by which needs of industry can be considerably satisfied. (C) 2014 Elsevier B.V. All rights reserved.