Industrial Heap Bioleaching of Copper Sulfide Ore Started with Only Water Irrigation

Sulfuric acid solution containing ferric iron is the extractant for industrial heap bioleaching of copper sulfides. To start a heap bioleaching plant, sulfuric acid is usually added to the irrigation solution to maintain adequate acidity (pH 1.0–2.0) for copper dissolution. An industrial practice of heap bioleaching of secondary copper sulfide ore that began with only water irrigation without the addition of sulfuric acid was successfully implemented and introduced in this manuscript. The mineral composition and their behavior related to the production and consumption of sulfuric acid during the bioleaching in heaps was analyzed. This indicated the possibility of self-generating of sulfuric acid in heaps without exogenous addition. After proving by batches of laboratory tests, industrial measures were implemented to promote the sulfide mineral oxidation in heaps throughout the acidifying stages, from a pH of 7.0 to 1.0, thus sulfuric acid and iron was produced especially by pyrite oxidation. After acidifying of the heaps, adapted microbial consortium was inoculated and established in a leaching system. The launch of the bioleaching heap and finally the production expansion were realized without the addition of sulfuric acid, showing great efficiency under low operation costs.

Molecular modelling and synthesis of a new collector O-butyl S-(1-chloroethyl)carbonodithioate for copper sulfide ore and its flotation behavior

Based on the homology principle in advanced pharmaceutical chemistry, a new high efficiency and low toxicity collector, O-butyl S-(1-chloroethyl)carbonodithioate, was designed.

Accelerating Copper Leaching from Sulfide Ores in Acid-Nitrate-Chloride Media Using Agglomeration and Curing as Pretreatment

This work investigates the effect of an agglomeration and curing pretreatment on leaching of a copper sulfide ore, mainly chalcopyrite, using mini-columns in acid-nitrate-chloride media. Ten pretreatment tests were conducted to evaluate different variables, namely the addition of nitrate as NaNO3 (11.7 and 23.3 kg/ton), chloride as NaCl (2.1 and 19.8 kg/ton), curing time (20 and 30 days) and repose temperature (25 and 45 °C). The optimum copper extraction of 58.6% was achieved with the addition of 23.3 kg of NaNO3/ton, 19.8 kg of NaCl/ton, and after 30 days of curing at 45 °C. Under these pretreatment conditions, three samples of ore were leached in mini-columns. The studied parameters were temperature (25 and 45 °C) and chloride concentration (20 and 40 g/L). The optimum copper extraction of 63.9% was obtained in the mini-column leaching test at 25 °C, with the use of 20 g/L of chloride. A higher temperature (45 °C) and a higher chloride concentration (40 g/L) negatively affected the extraction. The pretreatment stage had favorable effects, in terms of accelerating copper dissolution and improving leaching of copper sulfide ore in acid-nitrate-chloride media. Waste salts from caliche industry and waste brine from reverse osmosis can be used for providing the nitrate and chloride media.

BIOLEACHING OF COPPER FROM CARAIBA MINE ORE (BRAZIL)

The bioleaching of copper ore from the Caraiba Mine was assessed. A microorganism, Acidiothiobacillus ferrooxidans, was isolated from samples collected directly in acid mining drainage in a gold mine tailings pound and used in the bioleaching of the copper sulfide ore. This ore is composed mainly of 28% of oxidized species, 43% of secondary sulfides and 24% of primary sulfide. The shaking flasks experiments with the Caraiba ore showed copper chemical leaching of about 37% and copper bioleaching of about 60% within 60 days at low temperature and native microorganism.