Development of zero conditioning procedure for coal reverse flotation

An overview of reverse flotation process for coal

“…The feed ash of 34.6% showed a yield of 50.4% at product ash of 16.7% at an optimum value of pH in the range of 7.5 to 8.4. The aforementioned procedure of zero-conditioning was tested for reverse flotation by Patil and Laskowski (2008) on both batch and continuous processes. In the batch zero conditioning, the required amount of DTAB was added in one step when the air was introduced into the system whereas for the continuous zero conditioning method, a specially built sparger was used for uninterrupted DTAB addition in the form of aerosol during the flotation experiment.…”

“…In this regard, the depressants play a critical role by rendering the coal hydrophilic in nature and thus enhancing the selectivity of the process. Except Eveson (1961) who used potassium permanganate, potassium dibromate, persulphates and hypochlorites, the more commonly used coal depressants are either the organic colloids such as dextrin and starch or humic acid (Miller, 1975;Miller et al, 1984;Lin, 1982;Ding and Laskowski, 2006a,b;Melo, 2005;Zhang et al, 2013;Pawlik and Laskowski, 2003a,b;Pawlik, 2002;Patil and Laskowski, 2008). The depressing action of quaternary amines was also investigated by Stonestreet and Franzidis (1988) which did not give encouraging results and so they used dextrin in their later works (Stonestreet and Franzidis, 1992).…”

“…Eveson (1961), Pawlik and Laskowski (2003b) and Zhang et al (2013). In the rest of the works (Stonestreet and Franzidis, 1988, 1992Ding and Laskowski, 2006a,b;Patil and Laskowski, 2008) no frother has been used as the quaternary amines also display frothing properties apart from their ash collecting ability. Melo (2005) studied the frothing action of DTAB along with five other conventional frothers.…”

“…In the case of coal flotation, it is well known that best results are obtained at particle size below 300 μm. Essentially all of the work done on coal reverse flotation has abide by this either in the form of fully liberated feed as coal/gangue mixture (Stonestreet and Franzidis, 1988, 1992Pawlik and Laskowski, 2003a,b;Ding and Laskowski, 2006a) or finely ground coal samples (Melo, 2005;Ding and Laskowski, 2006b;Patil and Laskowski, 2008;Zhang et al, 2013;Pawlik, 2002;Vamvuka and Agridiotis, 2001). Vamvuka and Agridiotis (2001) studied the response of individual size fractions (+300 μm, −300 + 75 μm and −75 μm) using a mixture of kerosene having 2% DDA as collector and MIBC as frother.…”

“…The concept was further developed for the selective removal of pyritic sulphur from US coals by several investigators (Baker et al, 1973;Miller, 1973Miller, , 1975Miller and Deurbrouck, 1982;Lin, 1982;Miller et al, 1984). Consequently the study of reverse flotation of coal with a motive to lower the ash content of coal was carried out by many scientists and researchers (Stonestreet and Franzidis, 1988, 1992Vamvuka and Agridiotis, 2001;Pawlik and Laskowski, 2003a,b;Melo, 2005;Ding and Laskowski, 2006a,b;Patil andLaskowski, 2008, Zhang et al, 2013;Ozturk and Temel, 2013;.…”