Just some Notes :arrow:
http://goldrefiningforum.com/phpBB3/viewtopic.php?p=39516#39516
Pre-oxidation of high-sulfur and high-arsenic refractory gold concentrate by ozone and ferric ions in acidic media
Qingcui Lia, Dengxin Li , a, , and Fangjun Qiana
aCollege of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Songjiang District, Shanghai 201620, China
Received 28 September 2008;
revised 13 January 2009;
accepted 14 January 2009.
Available online 22 January 2009.
Abstract
Owing to precious metals and hazardous elements contained in high-sulfur and high-arsenic refractory gold concentrate (HGC), effective treatment of HGC can have both economic and environmental benefits. In this paper, pre-oxidation HGC by ozone and Fe (III) in acidic media and subsequent cyanide leaching of the pretreated ores were investigated. An L9 (four factors in three levels) standard orthogonal array was employed to evaluate the effects of ferric concentration, reaction temperature, reaction time, and liquid to solid ratio on ferric extraction from HGC. Statistical techniques were used to determine that reaction temperature was the most significant factors affecting ferric extraction. Furthermore, the results of factorial experiments showed ferric extraction increased with an increase of ozone concentration, liquid to solid ratio and temperature, but was independent of stirring speed when the speed was above 860 rpm. Also, the selected oxidized residues after the pretreatment process were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and subjected to subsequent cyanide leaching tests. Gold extraction after pre-oxidation under optimum conditions increased from 19.5% of direct cyanide leaching to 96.5%.
Keywords: Pre-oxidation; Ozone and ferric sulfate; Orthogonal experiment; High-sulfur and high-arsenic refractory gold concentrate
Ozone will oxidize metals except gold, platinum, and iridium to oxides of the metals in their highest oxidation state. Ozone can be used to remove manganese from the water, forming a precipitate which can be filtered. The highest levels of ozone in the atmosphere are in the stratosphere, in a region also known as the ozone layer between about 10 km and 50 km above the surface. Here it filters out the shorter wavelengths less than 320 nm of ultraviolet light 270 to 400 nm from the Sun that would be harmful to most forms of life in large doses. These same wavelengths are also among those responsible for the production of vitamin D, which is essential for human health. Ozone can be used for bleaching substances and for killing bacteria. Disinfect laundry in hospitals, food factories, care homes etc, Disinfect water before it is bottled, deodorize air and objects, such as after a fire, kill bacteria on food or on contact surfaces, scrub yeast and mold spores from the air in food processing plants, wash fresh fruits and vegetables to kill yeast, mold and bacteria, chemically attack contaminants in water such us iron, arsenic, hydrogen sulfide, nitrites, and complex organics lumped together as color, provide an aid to flocculation (agglomeration of molecules, which aids in filtration, where the iron and arsenic are removed).
