Extremophiles in Mineral Sulphide Heaps: Some Bacterial Responses to Variable Temperature, Acidity and Solution Composition

Abstract

In heap bioleaching, acidophilic extremophiles contribute to enhanced metal extraction from mineral sulphides through the oxidation of Fe(II) and/or reduced inorganic sulphur compounds (RISC), such as elemental sulphur or mineral sulphides, or the degradation of organic compounds derived from the ore, biota or reagents used during mineral processing. The impacts of variable solution acidity and composition, as well as temperature on the three microbiological functions have been examined for up to four bacterial species found in mineral sulphide heaps. The results indicate that bacteria adapt to sufficiently high metal concentrations (Cu, Ni, Co, Zn, As) to allow them to function in mineral sulphide heaps and, by engaging alternative metabolic pathways, to extend the solution pH range over which growth is sustained. Fluctuating temperatures during start up in sulphide heaps pose the greatest threat to efficient bacterial colonisation. The large masses of ores in bioleaching heaps mean that high temperatures arising from sulphide oxidation are hard to control initially, when the sulphide content of the ore is greatest. During that period, mesophilic and moderately thermophilic bacteria are markedly reduced in both numbers and activity.

A Brief Note on the Heap Leaching Technologies for the Recovery of Valuable Metals

“…These were highly effective on the production capacity of copper. It is possible to recover 60% of copper through heap bioleaching [19]. The authors discussed an appropriate pad design for high leaching efficiency in the brief reviews [20,21] on the heap pad designing criteria, pad characterization program, pad types, operational kinetics, material handling, and risk assessments.…”

“…Summary of leaching methods for the extraction of different metals with recovery efficiencies[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].The extractions of 52% Cu, 95% Ni and 85% Co were achieved in 30 days (65 • C) by heap bioleach. If cyanide leach process (23 • C) can be operated in 21 days, 20.3% Pt, 87% Pd and 46% Rh, if 50 days or more to achieve 50% platinum.…”

Разработка Комплексной Технологии Извлечения Золота Из Хвостов Смешанного Состава Майкаинской Обогатительной Фабрики

“…В результате тонкодисперсное золото высвобождается и может быть пригодно для цианирования. Полученные результаты подтверждают тот факт, что в процессе предварительного окисления и цианидного выщелачивания железосодержащие минералы разрушаются и частично переходят в раствор [11][12][13][14][15].…”

Composition of aboriginal consortium of microorganisms from coal mines dumps

“…Similar processes have occurred in the technogenic wastes which de rived from the corresponding natural substrates [16,24,29,41]. The processing of pri mary mineral raw materials in the hostile environment and further accumulation and preservation of generated waste and heaps with changing of temperature, acidity, con tent of high concentrations of heavy metals have made conditions for a wide variety of their own microbiota [16,17,34]. The problems connected with structure and balance of different groups of microorganisms, physiological and biochemical characteristics and practically useful properties of bacteria which lived in these man made ecosystems are underexplored [6,16,30,35].…”