Mar 01, 1998· 3.1.3. Influence of thiourea concentration on gold dissolution. The influence of thiourea concentration on the leaching of gold was investigated by varying CS(NH 2) 2 in the range from 10 to 100 g/kg. Fe 2 (SO4) 3 concentration was fixed at 0.5 g/kg, .
T1 - THIOUREA LEACHING OF GOLD AND SILVER - TECHNOLOGY UPDATE AND ADDITIONAL APPLICATIONS. AU - Hiskey, J. B. PY - 1984/12/1. Y1 - 1984/12/1. N2 - The review of recent literature relating to the use of thiourea as a lixiviant for gold and silver indicates only .
Apr 27, 2007· Even the traditional cyanidation process has been modified during the course of time to make it more economical and efficient. Developments such as heap leaching, in-situ leaching, carbon-in-pulp (CIP), carbon-in-leach (CIL) resin-in-pulp (RIP), and pretreatment of refractory ores have already made an impact on gold industries.
The reduction of gold(I)-thiourea occurs24,29-33 according toreaction (2)and isdiffusion controlled at cathodic overpotentials between -0,15 and -0,35V, after which slight inhibition occurs29.Atthepeak ofthe curve forcathodic current versus potential (Fig. 1),the
In order to determine the maximum size to which an ore may be ground for CLS leaching, thiourea leaching, or any kind of leaching, a number of tests should be run. One can rough grind to -40 mesh or even -20 mesh and run several CLS 2 tests on 2 pounds or one ounce of ore (See Chapter 7 .
Leaching of gold using cyanide is a widely used process throughout the mining industry and is credited to be relatively cheap to implement. A problem has been encountered with the use of cyanide in double refractory ores. Sulfides such as pyrrhotite and pyrite (FeS-Fe 7 S 8) are
Gold cyanidation (also known as the cyanide process or the MacArthur-Forrest process) is a hydrometallurgical technique for extracting gold from low-grade ore by converting the gold to a water-soluble coordination complex.It is the most commonly used leaching process for gold extraction.. Production of reagents for mineral processing to recover gold, copper, zinc and silver represents ...
It is used in gold and silver leaching. Lixiviants are used for this purpose and thiourea is an important ingredient of these. Health Hazards from Thiourea Even short exposure of the thiourea can cause irritation and temporary skin infection. 125mg/kg of thiourea can be lethal for rats on oral ingestion.
If the gold can not be concentrated for smelting, then it is leached by an aqueous solution: . The cyanide process is the industry standard.; Thiosulfate leaching has been proven to be effective on ores with high soluble copper values or ores which experience preg-robbing: the absorption by carbonaceous components which preferentially absorbs gold and gold-cyanide complexes.
A leaching agent for gold leaching and silver leaching can be created by selectively oxidizing thiourea, bypassing the steps of cyanide use and smelting. Another common application for use of thiourea is a common sulfur source for making semiconductor cadmium sulfide nanoparticle.
Table of ContentsAdsorption Gold Thiourea & Cation Exchange ResinThiourea ConcentrationThiourea Consumption during Gold Leaching The use of thiourea, (CS(NH2)2 as a complexing/extracting agent for gold and other precious metals has shown promise for implementation in the mining/metals industry. Laboratory testing of this reagent has indicated that a thiourea process for gold extraction has ...
Leaching with a relatively concentrated thiourea solution (1MCS (NH 2) 2) resulted in 83% gold and 75% silver extraction in four hours. With the treated flue dust residue, gold extraction was about 60%. Gold and silver extraction with cyanide was sensitive to .
A method is provided for recovering gold and silver from precious metal bearing materials including ores, leaching residues, flue dust, electronic scrap, jewelry scrap, etc. In the method, the gold and silver are extracted from the precious metal bearing materials with a thiourea solution to form a thiourea leach, and the thiourea leach is contacted with carbon to adsorb the gold and silver ...
Leaching Pyrite Gold Ore without Cyanide. Thiourea Leaching of Gold. The use of thiourea for gold leaching has been proposed as a process alternative due to the supposed lower toxicity, faster leaching kinetics and the alleged less interference from base metals as compared to cyanide (Sparrow and Woodcock, 1995).
The objective of this work was to recover gold and silver from the printed circuit board (PCB) of discarded mobile phones by thiourea leaching. Effects of thiourea concentration, leaching temperature, leaching time, and ferric ion (Fe3+) concentration on the recovery of gold and silver were investigated. The PCB was pretreated physically to reduce the thiourea consumption and enhance the ...
Oct 23, 2006· Since the initial report of thiourea as a complexing reagent for gold leaching, considerable research has been directed toward the use of thiourea as an alternative to cyanide for gold extraction from different auriferous mineral resources. At the same time, some fundamental investigations of the system have been reported.
Feb 01, 2011· The gold leaching rate decreases with time and ferric concentration has only a minor effect on the rate of gold dissolution. (2) A u + F e 3 + + 2 S C N − → A u (S C N) 2 − + F e 2 + In thiourea–thiocyanate solutions, the gold leaching rate remains constant with time, which means the mixed ligand exhibits behavior similar to thiourea ...
lurgical gold extraction routes utilize a leaching step to produce a gold-bearing solution as an intermediate product while the recycling of secondary gold from electronic and precious metal scrap is based on the selective and fast dissolu-tion of the precious metal. Therefore, A Method for Leaching or Dissolving Gold from Ores or Precious
1. Introduction. The use of thiourea (SC(NH 2) 2) (TU) has been studied extensively, mainly because it is not harmful to the environment, nontoxic to human beings, and the dissolution of gold in thiourea solutions is much faster than in cyanide solutions.The dissolution of gold in thiourea solutions was reported for the first time in 1941, and it was continued in 1960 [1] .
The invention relates to modifications of a non-ammoniacal thiosulfate process of leaching precious metals (e.g. gold or silver) from precious metal-containing ores. The process involves leaching the ore with an aqueous lixiviant containing a soluble thiosulfate other than ammonium thiosulfate, a copper compound and an organic compound that serves as a copper ligand (i.e. a ligand-forming ...
Other chemicals have been used to leach gold, and they include bromine, chlorine, and thiourea. There has also been a lot of experimentation with various biological media for recovering gold from ores, but no one has come up with a more cost effective and productive method than leaching with cyanide.
The chemistry of thiourea is simpler than thiosulfate complexation with gold, forming a cationic complex of gold. Various oxidants like oxygen, ozone, sodium peroxide, hydrogen peroxide, ferric ions, dichromate, and manganese dioxide are employed to enhance the leaching of gold in thiourea solution.
The acidic leaching using Thiourea, required more chemical reagents and maximum gold recovery of 90.48% was achieved with Thiourea consumption, leaching .
sively for leaching gold and silver since its introduction 100 yr ago. Recently, there has been mch interest in the min- ing and metallurgical processing indus- tries in thiourea as an extractant for gold and silver (1-3, -- -- 6-14).3 Thiourea extracts gold in an acidic .