Q.
Even if I know nothing about extracting gold from primary ores or re-cycling dumps, will the information contained in this guide help me get set up?
A.
The information in this guide, while of a technical nature, is set out in such a way as to be both comprehensive and understandable to both novice and established operators alike. Many of the techniques are explained in a step-by-step procedure, supported by tried and tested quantities and measurements for both the chemical and mechanical means of isolating gold. However, attempting any gold isolation technique as a novice will require some degree of technical competence.
Q. Has this guide been written with techniques and equipment applicable to a specific country or part of the world, or can they be used anywhere?
A. Gold has specific properties that behave in a predictable manner (i.e. high S.G.). These properties have been exploited by both mechanical and chemical means of recovery for centuries, all over the world. While equipment, materials and methods vary, from simplistic in developing-countries to First World high-tech., ultimately, operators achieve the same result, albeit with varying degrees of efficiency. Some of the chemical means of gold isolation within this guide may be affected by local governmental and environmental protocols that ban, restrict or regulate the use of hazardous substances, such as sodium cyanide or mercury. In this instance, the section on cyanidation will be irrelevant to those operators working under strict environmental regulations. Accidents and spills involving sodium cyanide led to the development of a voluntary industry program by cyanide producers, regulatory personnel, mining companies and environmental advocacy organizations to address the problem ("International Cyanide Management Code for the Manufacture, Transport and Use of Cyanide in the Production of Gold"). In these circumstances alternative chemical extraction methods such as in-situ (solution) leaching with halides (chlorine) should be investigated. This methodology is not commonly practiced; however its key attributes are summarised in some detail (section 15) for completeness' sake.
Q. Some of this guide addresses applications and procedure that appear to be 'out-dated'', such as stamp milling. Just how modern is the information in this guide?
A. The approach of this guide is to address both the old and new, low-tech. and high-tech., and aimed at the small-scale operator with a modest budget. Many Third World countries for example, still utilise stamp milling as a means of ore reduction, such as South Africa, Zimbabwe and Tanzania. This means of crushing is widely practiced and small-scale stamp mills are still manufactured and distributed to these countries. For this reason, a chapter on this method of ore-reduction has been included. Cyanidation of residue dumps and ores hosting fine particulate gold is a common practice in these countries and while frowned on in some developed countries with strict environmental codes (e.g. New Zealand), this chemical method of gold isolation is included here to benefit those small scale operators. Overall, the information in this guide is meant to address ore beneficiation over a wide spectrum - from the older techniques still in practice, to more the modern methods of ore-beneficiation.
Q. Gold is mined from both hard-rock and alluvial (secondary) gold deposits, as well as residue dams (tailings). Many of these deposits have a high, coarse free gold component that can be recovered by tabling or jigging, while the fine gold component is lost to tailings. What if the ore is difficult to process with the gold either being locked-up in sulphides or a high percentage of it reporting to the fine tailings as flower-gold? Does the guide address gold extraction from 'problem-ores?
A. This guide addresses these problems quite comprehensively and the section 10, 'Difficulties and Remedies in the Treatment of Problem-Ores' deals with this issue in some detail (18 A4 pages).
