Management of Stibnite Deposition at Ngawha

Abstract

Soun after comm&shnhg of&e 'Eu'gawha G e & d Power SttZtton, deposih~ probhs m the geo&mE side of &e brbefpen-tane heat exchangers were experienced. The deposit consists almost entirely of antimony sulphide and has continued to occur at such a rate that removal has been necessary at least every six months. As a practical means of prevention has not been found, refmement of removal techniques has been the focus of work on the problem. With deficiencies in the options for mechanical removal, a chemic4 removal technique has been developed. This uses a hot concentrated solution of NaOH, and trials to date have proved very successfil. It is likely that this procedure will become the main toot in combating stibnite deposition which is gohg to be a serious problem for any present or fbture operation at Kgawha.