Mine Drainage and Surface Mine Reclamation. Volume I: Mine Water and Mine Waste. Vol. I. Pittsburgh, PA: U.S. Bureau of Mines, 1988 Apr; :109-116
The effectiveness of sodium lauryl sulfate (SLS), potassium benzoate, and potassium sorbate in controlling the population of iron-oxidizing bacteria, thereby reducing acid production, was tested on sulfide tailings and waste rock, common waste products of metal mining. The waste rock was unweathered and contained 4.07 percent total sulfur, all in the pyritic form. Two different samples of sulfide tailings were used, an extensively weathered material (5.98 percent total sulfur, 0.17 percent pyritic sulfur, and 5.81 percent sulfate sulfur) and a slightly weathered material (20.57 percent total sulfur, 19.73 percent pyritic sulfur, and 0.84 percent sulfate sulfur). Two sample sizes were used in the experiment, 7 kg and 100 kg. The 100-kg samples of each material were treated once with a 600-mg/kg dose of SLS or potassium benzoate. The 7-kg samples were treated with a high (600 mg/kg) or low (60 mg/kg) dose of SLS, potassium benzoate, or potassium sorbate. The treated samples and untreated control samples were subsequently leached once per week with filtered demineralized water (an amount equivalent to 2.5 cm of precipitation). For the 100-kg samples of the waste rock, a single treatment of SLS and potassium benzoate completely inhibited iron-oxidizing bacteria repopulation for 182 and 231 days, respectively. Acidity in the leachate from the 100-kg samples treated with SLS and benzoate remained below the untreated control for 287 and 343 days, respectively. Similar results were obtained from the 7-kg samples of waste rock. In the extensively weathered sulfide tailings, none of the treatments inhibited the iron-oxidizing bacteria or reduced acidity levels in the leachate. In the slightly weathered sulfide tailings, all treatments reduced the bacterial populations, but did not significantly reduce acid production. However, in additional tests of the slightly weathered tailings, the removal of the weathered products prior to treatment with SLS or benzoate resulted in lower populations of iron-oxidizing bacteria and reduced acidity levels.