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

Although the main cause of hydrometallurgical plant closures is the depletion of oxidized copper minerals reserves, the lack of new hydrometallurgy projects also contributes to these closures. One solution is to be able to process copper sulphide ores hydrometallurgically. However, it is widely known that sulphide copper ores—and chalcopyrite in particular—have very slow dissolution kinetics in traditional leaching systems. An alternative to improve the extraction of copper from sulphide ores is the use of a pretreatment process. Several investigations were developed evaluating the effects of pretreatment, mainly in the extraction of copper from chalcopyrite in chloride media. This study presents a review of various pretreatment methods prior to heap leaching to aid in the dissolution of copper from sulphide ores. Different variables of pretreatment that affect the extraction of copper were identified, including the type of salts used in agglomeration, curing time, and curing temperatures. Successful cases such as the implementation of the CuproChlor® process (use of calcium chloride), and various pilot studies using sodium chloride and temperature, show that pretreatment is an alternative that aids in the dissolution of copper from sulphide ores.

Section: Introductionmentioning

confidence: 99%

Pretreatment of Copper Sulphide Ores Prior to Heap Leaching: A Review

Neira

Pizarro

Quezada

et al. 2021

“…Sodium nitrate in an acid medium provides an option for possible leaching of many sulfide minerals, including chalcopyrite, at an acceptable kinetic rate due to the high proton activity created by the presence of sodium nitrate, and a strong oxidizing agent [14]. Sodium nitrate has been used as an oxidizing agent for more than 130 years [15].…”

Section: Introductionmentioning

confidence: 99%

“…When NO x is in contact with an alkaline solution of NaOH, it forms nitrite and nitrate ions. The liquid phase reactions are presented from reaction (12) to (14). The nitrogen oxides (NO 2 , N 2 O 3 , and N 2 O 4 ) are scrubbed in the liquid film phase [31] but the selectivity is poor which leads to the formation of a mixture of nitrite and nitrate ions [29].…”

Section: Introductionmentioning

confidence: 99%

“…The nitrogen oxides (NO 2 , N 2 O 3 , and N 2 O 4 ) are scrubbed in the liquid film phase [31] but the selectivity is poor which leads to the formation of a mixture of nitrite and nitrate ions [29]. According to Suchak et al [29] chemical reactions (12) to (14) show that NaNO 2 is more selective than NaNO 3 and NO 2(g) captured in the aqueous solution is generally produced through disproportionation reactions:…”

Section: Introductionmentioning

confidence: 99%

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An Alternative Process for Leaching Chalcopyrite Concentrate in Nitrate-Acid-Seawater Media with Oxidant Recovery

Castellón

Hernández

Velásquez-Yévenes

et al. 2020

Self Cite

An alternative copper concentrate leaching process using sodium nitrate and sulfuric acid diluted in seawater followed by gas scrubbing to recover the sodium nitrate has been evaluated. The work involved leaching test carried out under various condition by varying temperature, leaching time, particle size, and concentrations of NaNO3 and H2SO4. The amount of copper extracted from the chalcopyrite concentrate leached with seawater, 0.5 M of H2SO4 and 0.5 M of NaNO3 increased from 78% at room temperature to 91% at 45 °C in 96 h and 46 h of leaching, respectively. Gas scrubbing with the alkaline solution of NaOH was explored to recover part of the sodium nitrate. The dissolved salts were recovered by evaporation as sodium nitrate and sodium nitrite crystals.

“…The addition of NaCl and sulfuric acid would promote the formation of polysulfides more soluble in aqueous media, and in the presence of chloride ions, the elementary sulfur layer is more porous, facilitating the diffusion of the reagents to its inside. That porosity promotes the formation of HCl and sodium sulfate [12][13][14][15][16]. The resting time of pre-treatment is another variable of interest.…”

Section: Introductionmentioning

confidence: 99%

Effect of Pre-Treatment with Sodium Chloride/Sulfuric Acid on the Bornite Concentrate Leaching in Chloride Medium

Navarro

Vargas

Bahamonde

et al. 2020

In this work, the effect of the pre-treatment of bornite concentrate with a sodium chloride–sulfuric acid mixture prior to leaching with chloride solutions was evaluated. The influence of the dosage of NaCl and the resting time in the copper solution was evaluated. The solid residues of the pre-treatment were characterized by XRD to evaluate the changes that took place in the bornite. The experimental results show that as the sitting time and the amount of sodium chloride added are increased, the dissolution of the sulfide species also increased. The pre-treatment affects Cu preferentially because it has greater mobility than iron in the bornite crystal lattice. The pre-treatment promotes the formation of soluble Cu and Fe species. The efficiency of the pre-treatment depends largely on the formation of hydrochloric acid in the mixture at the particle level, due to the ease with which it diffuses through the bornite particles, achieving greater penetration of the pre-treatment.