Gold (Precious Metal)Gold (Precious Metal)v Gold is a precious metal, as are silver and the platinum group metals

(platinum, palladium, rhodium, iridium, ruthenium and the extremely rareosmium).

v They are called precious metals because of their great resistance tochemical (and environmental) attack, because of their scarcity and,particularly in the case of gold and silver, because of their universal use injewellery.

v They frequently occur in nature as “native” metals, that is in the metallicstate and not as compounds, though often they are in combination withother metals in mineral form, and frequently in combination with eachother.

v Because of their strong resistance to chemical attack, techniques forseparating the individual precious metals are often complex, particularlythose for the platinum group metals (pgm’s).

Why should we need to enter in the Why should we need to enter in the Gold Gold Refinery process business?Refinery process business?v Refineries are quite lucrative businesses. It's all really about services or

processes.

vWhy refinery process is required ? No one can do any work without profit.. Inthis Refinery process , the profit occurs in all the ways. Actually in thisrefinery process profits will be for each and every material and there is nowastage.

Lets see how many ways are there getting profits while doing refinery process:

vWhile selling the scrap gold , it can be assay it, to find out exactly whatpercentages of what metals has been provided them. In such a wayfor finding to provide the output charges are applicable. The first profit willbe for the "Serving charge"

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why should we need to enter in the refinery gold process business?

v Then for using acids to dissolve some metals and not others to purify thevaluable metals.

v If Suppose for selling some gold scrap getting second profit. For exampleselling some 14K gold scrap. actually the sold gold scrap consists of metalalloy of 58% gold, 20-25% silver, and 12-7% copper by weight.

v Proportions vary by different alloys, but the Karat of gold is always a fractionof 24. 24K is 99.9% pure and 12K is 50% pure.

v Anyway, getting payment for the gold, at less than 58% what gold traded foron the day they receive the shipment because the gold sold was scrap,therefore of a lesser value because it needs to be processed (by them) to beof pure value again.

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Why should we need to enter in the Why should we need to enter in the Gold Gold Refinery process business?Refinery process business?

v Another way of profit for devalued rate for scrap, and in case it has beenmissed it, both silver and copper have a value, and are traded ascommodities, but the refinery probably won't pay for the other metals inthe alloy. Though it may not be as big a number as the gold, they deal involume and the little numbers add up.

v By the very process of removing the impurities they increase the value ofthe metal, and that is the main making profit. Used metal has less value aspure, unless it has historical or sentimental value.

v If a refinery has purified an alloy into it's purest state, the metal is in a morerare state. The laws of supply and demand follow. Since refineries are themain source of pure metal, they stand to make the first, and most, profitfrom the refining process.

Why should we need to enter in the Why should we need to enter in the Gold Gold Refinery process business?Refinery process business?

Gold RefiningGold RefiningIt has been seen that the various gold-containing materials available to thegold refiner, whether primary material from mines or natural sources or scrapgold products, have a high probability of containing silver and copper, andfrequently may contain other base metals and platinum group metals.

For the purposes of discussing the refining techniques, it is thereforeassumed that the refinable gold material also contains silver, pgm’s and basemetals and their behaviour in the processes will be addressed in turn.

Metal refining is made up of two types:v Primary: Primary refining is the refining of gold ore from the groundv Secondary: Melting of scrap down to a fine gold product is considered

secondary refining.

There are many techniques from which gold can be extracted, in both primaryand secondary refining.

Bullion PurityBullion Purity

bullion Purity can be fineness of

v995 in parts per thousand.

v999 in parts per thousand.

v999.9 or 999.99 in parts per thousand.

RefinableRefinable MaterialsMaterials

REFINABLE MATERIALS:

vMined Gold

vAlluvial Gold

vScrap Jewellery

vScrap Dental Alloys

vOther Gold Materials

Assaying of GoldAssaying of Goldv Before gold can be sent to the smelter, it must either be weighed, in the

case of scrap gold, or the customer and the smelter must agree on theestimated metal to gold content before extraction.

v Assayers take a drilled sample of gold bullion from the customer and sendit off to a lab to determine the precious metal content within the bullion.The assaying process is a condensed refining process that allows thecontent of precious metals to be discovered.

v Assay results must agree with the multiple tests that are performed and ifthey do not, the samples are melted again to make it homogeneous andtested again. Sweeps, which tend to be a lower quality gold, areincinerated to burn all combustibles then converted into a finehomogeneous powder.

v After this process, the powder can then be sent to an assayer to determinethe precious metal content through samples.

Assaying TechniquesAssaying Techniques

Types of Assaying Techniques:

vFire Assay

vICP Spectrometry

vX-Ray Fluorescence

vTouchstone

vDensity measurement

Gold Refining MethodsGold Refining Methods

Types of Refinement

Seven methods are commonly employed for purification:

MILLER PROCESSMILLER PROCESS

WOHLWILL PROCESSWOHLWILL PROCESS

INQUARTATION AND PARTINGINQUARTATION AND PARTING

FIZZER CELLFIZZER CELL

AQUA REGIAAQUA REGIA

CUPELLATIONCUPELLATIONPYROMETALLURGICALPYROMETALLURGICAL

Miller ProcessMiller Process

v The Miller industrial process refines scrap metal with an unknown butmeasurable content of gold into gold with a purity of 98 to 99 percent.

v The Miller process begins when scrap metal is melted into chunks smallenough to put into crucibles, using a furnace and some form of granulator.

v Granulators make the gold chips look like corn flakes, with a high surfacearea, so that during the chemical process all gold is thoroughly treated.The gold flakes are put into a crucible, which is heated until the metalbecomes molten, and then aerated with chlorine gas.

v The chlorine gas reacts with all metal that isn't gold, so that the chloridescreated can be separated from the gold, creating a fine product.

Outline of Miller Refining ProcessOutline of Miller Refining Process

WohlwillWohlwill ProcessProcess

v The Wohlwill process produces gold of a purity greater than 99.99 percent.

v The Wohlwill process involves electrolysis, in which an ingot of more than95 percent gold is suspended in chloroauric acid. The ingot is called theanode; the cathodes, 24 karat gold strips, are also floating in the chamber.

v Electric current is run through the chloroauric acid, and the acid andelectrolysis dissolve the anode and collect pure gold on the cathodes.These cathodes are taken out and melted down into fine gold.

v Often industry locations use first the Miller process followed by theWohlwill process, although the Wohlwill process is more expensive,requires more equipment and requires high gold inventories.

Outline of Outline of WohlwillWohlwill Refining ProcessRefining Process

CupellationCupellation

v Cupellation is a refining process in metallurgy, where ores or alloyedmetals are treated under high temperatures and controlled operations toseparate noble metals, like gold and silver, from base metals like lead,copper, zinc, arsenic, antimony or bismuth, present in the ore.

v The process is based on the principle that precious metals do not oxidize orreact chemically, unlike the base metals; so when they are heated at hightemperatures, the precious metals remain apart and the others reactforming slags or other compounds.

Outline of Outline of Cupellation Cupellation ProcessProcess

InquartationInquartation and Partingand Partingv The technique mirrors part of the Fire Assay process used in the analysis

(assay) of gold. Inquartation involves initially diluting the gold in the refinablematerial to about 25% (literally ‘quartering' the gold) by melting with theappropriate addition of copper or silver, granulating the melt so as togenerate a high surface area and then treating with nitric acid.

v The acid will dissolve the silver and base metals, leaving behind the gold. Theacid treatment is known as parting as it ‘parts' (separates) the gold from thesilver and base metals. Dilution of the gold content is necessary to ensurethat the nitric acid can readily attack and dissolve the base metals and silver,some of which may be otherwise masked by the gold. Any palladium which isalloyed in the gold will also be removed by the acid.

Outline of Outline of InquartationInquartation & Parting & Parting ProcessProcess

Fizzer Cell ProcessFizzer Cell Process

v The Fizzer Cell Process is animproved Wohlwill Process whosemain change is the cathode design.There is a porous ceramic containerthat works like a membrane whosepurpose is to avoid gold losses andadhesion of some impurities oncathode surface.

v The electrolytic cell is drained andfiltered. A very important aspect ofthis process is referred to thepossibility of treating impureanodes, basically when the silvercontent is as high as 10%.

Outline of Outline of Fizzer Cell ProcessFizzer Cell Process

PyrometallurgicalPyrometallurgical ProcessProcessv This process is not strictly a refining process

but a means of converting scrap jewelleryalloys into clean gold-silver-copper alloysuitable for realloying into new jewelleryalloys.

v The principle is to smelt scrap gold alloy undera flux and to bubble air or oxygen through themolten metal to electively oxidise impuritiessuch as zinc, cadmium, iron, tin, lead. Theoxidised metal impurities combine with theflux to form a slag on the surface of the melt.Typically the reaction time can be about onehour and the end point is best determined byestimating the copper content of the slag.Detailed analysis of the metal is necessarybefore subsequent use.

Outline of Outline of PyrometallurgicalPyrometallurgical ProcessProcess

Aqua Aqua RegiaRegia ProcessProcess

v The Aqua Regia Process is appropriate to be employed in small scale and themetallic gold to be obtained is as pure as 99.9%. The main steps of theprocess are to dissolve the precious metals and some impurities. Since theAqua Regia is a mixture between nitric acid and hydrochloric acid, part ofthe silver will remain in solution and other part will form a silver chlorideprecipitate. Then, it is important to be careful with the silver content.

v It must be mentioned that the silver chloride formation has a negative effecton gold dissolution. Once the dissolution is performed, the solution and theprecipitate are separate by filtration operations. The solution contains goldand is treated with reducing agents such as ferrous sulphate, sulphur dioxideor sodium bi-sulphate. Gold powder of high purity is obtained and can bemelted later. When gold precipitates, platinum group metals remain insolution and have to be recovered by other procedure.

Outline of Outline of Aqua Aqua RegiaRegia ProcessProcess

PROCESSING METHOD

GOLD REFININGGOLD REFINING

Gold Refining ProcessGold Refining ProcessGold refining is a highly complex process which requires a deep understanding of material science, pyrometalurgy, multi stage

chemical separations and analytical science.

EVALUATIONEVALUATION

SMELTINGSMELTING

CHEMICAL LEACHINGCHEMICAL LEACHING

CHEMICAL SEPARATIONCHEMICAL SEPARATION

EvaluationEvaluation

v Evaluation is a critical stage in our pgmrefining process.

v During this step it determine the pgmcontent of the customer’s material to checkwith them what quantity or value of pgmrequired for them. return to them and thelead time for refining.

v Material tracking is crucial, and on receipt allcustomer batches are uniquely barcoded toensure full traceability during evaluation.

SmeltingSmelting

v Once terms are agreed feeds are no longerhandled on a customer by customer basis,but are combined together in much largerbatches for smelting.

v In this pyrometallurical process material ismelted at temperatures over 1200 C foraround 12 hours in large revertory furnacesto separate the non-metallic components.

v Two types of bullion feed are produced: asilver based feed containing primarilyplatinum and palladium, and an iron basedfeed which contains all five of the pgms.

Chemical LeachingChemical Leaching

v The two bullion feeds then move to thechemical leaching plant, where they undergomultiple leachings to further concentrate thepgms into solution.

v The silver based bullion is suspended inconcentrated acid to slowly leach the silver,platinum and palladium into solution andseparate out any gold.

v Gold impurities are sent for further refining.Silver is removed and further treated intosaleable products , some of which are used inother businesses in the group.

Chemical SeparationChemical Separationv Chemical separation is a highly complex

multistage process in which we separate out thefive pgms into their final product forms,commonly a pgm sponge, although other formsare produced depending on customerrequirements.

v The chemical separation process involves a seriesof solvent extractions, evaporation, dissolution,precipitation and filtration steps to producehighly pure orgometallic salts for each individualpgm.

v These salts then undergo several heattreatments steps to reduce them to the finalpure platinum group metal which is weighed andpacked, ready for dispatch to customers.

Gold Refinery MachineGold Refinery Machine

v Star Trace introduce the latest internationallyadopted method of chemical refining, the GoldRefinery has incorporated further improvementsto suit the refining needs of our own Biotechresearch and development facilities along withour indigeneous manufacturing capability Startrace is able to develop and produce world classtop of the line refineries.

v As with our other precious metal and preciousstone mining products Star Trace can provideproper training and prompt after-sales servicesupport as well as specialized consultancy for thespecific requirements of our clients.

Gold Refinery Machine Gold Refinery Machine -- FeaturesFeatures

v Refines gold scrap, filings, dust, sweepings, etc.

v Safer and Faster Processing.

v Latest Technology.

v Purifies Gold (Au) up to 999,9 and Silver (Ag) up to 995,0,

v Minimum handling of Equipments.

v Hazardous Fumes Neutralized through Gas treatment.

v Designed to be easily setup and quickly operational.

v Turnkey installation, user-friendly.

Gold Refinery Machine Gold Refinery Machine -- SpecificationSpecification

Note:1. Technical data specification subject to change2. Special Gold refinery machine can be made on request, Please send us Your’s Technical data and application, required for ourengineers to provide.

Gold Ore concentrate processing plantGold Ore concentrate processing plant

Gold ore concentrate with chemical &Gold ore concentrate with chemical &ElectrowinningElectrowinning processing plantprocessing plant

Gold ore preGold ore pre--concentrate processing plantconcentrate processing plant

Gold processing plantGold processing plant

Gold ore Processing Gold ore Processing equipmentsequipments

THANK YOUPresentation By

P.R.Maheswaran, Managing DirectorSTAR TRACE PVT. LTD.

No:7, Jeevanandham street, Red Hills,Chennai - 600 052, India.

Website: www.startraceltd.comPh: +91 044 26418456

+91 044 26419439