The Basics Sampling Science for Precious Metals Analysis

The process of taking small samples for analysis

The process of taking small samples for analysis to determine the precious metal content of a large quantity of material is the most critical. Small errors and sapling can there fore lead to large differences in the calculated value of each precious metal. Sampling science and techniques are used on primary sources of precious metals from ore samples at mine sites.

Due to the high value of precious metals very low concentrations are contained enviable primary or secondary sources. For example a platinum concentration as low as 2 to 3 grams per ton of ore or scrap material is often profitable to recover and refine.

The process of taking samples from drilling to analysis

Secondary sources of precious metals which are manufacturing scrap or end-of-life materials for recycling and  refining must also be sampled properly for accurate results.

The fundamental processes include preparation, homogenization, equation handling and splitting from bulk lots to prepare a small sample to represent the average composition of the large amount of material.

Homogenizing is the process by which the material is blended uniformly to facilitate accurate sampling. Splitting is the act of evenly dividing materials while avoiding any separation or segregation for example a typical sample size of 300 grams may be selected to represent the average composition of several tons of material once the 300 grand sample is sent to the analytical lab the sample will then be further split to obtain smaller samples used for analysis.

Homogenizing process

The science and techniques used at mine sites for obtaining or samples utilize complex statistical analysis. The same material from initial surface exploration is first panel sighs to determine locations for drilling core samples to map out or deposits and determine mind valuations.

Chip samples are also taken within an active mind. Evaluation or deposits are used to determine where to drill and to calculate the value of the ore which is required to secure financing for the mining operation.

Materials that contain precious metals for recycling and refining are collected in bulk lots it is critical to accurately determine what concentrations of each precious metal are contained in each lot for two reasons.

First is to obtain the technical information needed to determine which processes to use for refining or whether it is even worth the cost of refining.

The second is the financial consideration to place the correct value on each lot as the materials change hands from suppliers to fires. Samples are often analyzed by both parties and transactions with a third sample saved as a referee sample for possible analysis by an independent lab.

Video The Basics Sampling Science for Precious Metals Analysis

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Precious Metals Analysis For Sampling

Artisanal Gold Mining In West Africa

Province Loba 50 meters underground Since 2001, artisanal gold mining communities have sprung up around West Africa, In many respect it resembles the gold rush of the nineteenth century.

These cities were mere fields before they came artisanal miners. His arrival created wealth and a flourishing secondary economy that drove the development of regulations, systems of land tenure, infrastructure and economic diversification.

It is fascinating to see that almost the same phenomena that occurred in the gold rush are happening again today.

Although artisanal gold mining has been active since antiquity, the sector in West Africa has grown dramatically since 2001, driven by rising gold price and the lack of alternative opportunities.

Many farmers and herdsmen have entered the sector of artisanal gold mining and now they use their profits to improve their farming activities.

In artisanal gold mining, see a direct transfer of wealth which it is unique to other products sold on the international market.

For most agricultural products, for example, those who buy in the grocery store, only a small fraction of that profit back to the small original producer, often less than 20%.

Even for social brand products, the percentage is only moderately higher. For example, the banana cooperatives receive about a dollar for 18 kilos of bananas, less than 20%. On the other hand, artisanal miners earn a minimum of 70% to 80% of the international price.

This is unheard of in other goods. Artisanal gold mining is a massive wealth from rich to poor, but also has an amplification effect.

The local secondary economy is typically five or six times larger than the primary economy, the value of gold.

Miners use their profits to pay for hardware products, mining supplies, food, clothing, transportation, communications, medicine, all things that sell local businesses and people of that service sector, in turn do the same.

Thus they are circulating gold profits, building a large and diverse local economy. Motorcycle dealers, home improvement, telecommunications, health services, infrastructure and schools often appear in cities in connection artisanal gold mines.

Mercury is one of the great problems of artisanal gold mining. Mercury is cheap and therefore affordable means for processing the gold, but it is also a deadly neurotoxin that can cause permanent damage to the nervous system, and even death.

It is also a poor extraction method, which normally gets about 40% of the gold that is in the mineral, therefore wasting resource.

Artisanal Gold Mining In West Africa

Although problems like mercury poisoning, exposure to silica dust, child labor and other criminal activity may be present in artisanal mining sites around West Africa, governments often overlook the positive benefits.

Governments and the media have a history of condemnation and demonization of artisanal gold mining without really properly understand the sector without offering solutions.

However, artisanal gold mining is now universally recognized by international agencies like the UN as a development opportunity and a huge source of rural employment and wealth generation.

The modern sector of artisanal gold mining has been strong for some 40 years and because of the jobs it provides poor rural areas, it is clear that it will continue.

In fact, it is probably stronger than the industrial sector of gold mining, which it is much more susceptible to fluctuations in gold prices.

In this context, the government and industry should help artisanal gold mining to improve their environmental and social performance to allow maximize its role of reducing poverty.

Need help and support to enter the formal economy, where you can become a responsible sector and help finance a diverse and sustainable rural economy.

And this is where comes the Artisanal Gold Council (AGC). The Artisanal Gold Council is a non-profit organization dedicated to improving opportunities, the environment and health of the millions of people involved in artisanal mining and small-scale gold in the developing world, and in doing so, we are helping to improve the integrity of the entire gold sector, from small to large.

Artisanal Gold Council (AGC)
In West Africa

Video  Artisanal Gold Mining In West Africa

Problems Solutions and Opportunities

Poisoned By Gold Rush In Colombia

Traditional mining in Colombia

Poisoned by GOLD RUSH It is to Remedios, a traditional mining town in the region of Antioquia, a rich gold country in northern Colombia.

Mining has always been one of the main activities of the region, but in recent years the sector is booming.

A recent increase in the value of gold and the government's fight against coca cultivation led to unprecedented demand for the precious ore.

Today, gold is quickly becoming the new cocaine in Colombia. The explosion flooded the country of cash, sex, alcohol and debauchery.

But the exposure of children to mercury cheap technology to extract gold, had a negative impact.

In particular, many children find them selves powerless today. There is a problem of impotence in the region? It is a problem. It is usually attributed to mercury pollution in the region.

To meet the growing demand for gold, the number of underground mines exploded. Today, mercury pollution has become a serious problem in this region of Colombia. The mines destroy the jungle, dry rivers, and discharge of harmful pollutants in nature.

Today, about 80 percent of the gold mined in Colombia comes from these mines some of which help finance the guerrillas, and criminal or paramilitary groups.

It is a disputed territory for many years, and armed rebel groups trying to control the territory, because, of course, the wealth of natural. Illegal mining operations bring in about $ 2.

Traditional mining in Colombia

Gold grain for traditional mining in Colombia

5 billion a year, and are now more profitable than cocaine trade for Colombian armed groups, managing or impose farms.

Per kilo, the value of gold is greater than that of cocaine, and as it is a legal product, it is easier to sell. This is why young people like Didier Perea flock to the mines in the hope of making a fortune. 

Recently it became a business because there are mines where you start working and the salary minimum is very good.

Addict ? Yes, because sometimes we find gold, you take a barrel, washed and wins up to 5 million Colombian pesos (1,485 euros) for this piece, so inevitably it motivates us, and It gradually becomes addicted.

In this type of small-scale operations, Minors use mercury to separate gold from other materials. They are in constant contact with such a toxic material that even low levels of exposure can damage the nervous system.

Chronic mercury poisoning can cause organ failure and even death. For over 100 years this method is banned in the United States. 

Survey Mining In Afghanistan

Commercial drill rigs are a rare sight in Afghanistan. Problems affecting the country's infrastructure and instability have left mining projects in their infancy, but Afghanistan is a geological treasure trove.

"There is a working gold mine in Baghlan at the moment and in Sheberghan we've got gas and petrol. The north of Afghanistan has lots of mining opportunities.

In Jegdalek there are gemstones and in Mes Aynak there is copper, iron and chromium and other valuable minerals.

Drillers and geologists are among the first cohort of trainees from the Afghanistan Geological Survey being taught by the US Dod Task Force for Business and Stability Operations. The students are gaining the skills they need to explore and exploit the country's resources,by training in modern explorative techniques.

The next step for these drillers will be to push out into the country's mountains. Hope is that security will improve still, because there is still some insecurity in some of Afghanistan's provinces.

If the security improves, they will be able to go freely everywhere in Afghanistan to conduct surveys.

"And if Afghanistan's security does improve, the Afghan government will be first in line to exploit the nearly 3 trillion dollars of resources lying in its hills and mountains.

It's hoped that the mining sector could become one of the Afghan economy's strongest assets.

"There has effectively been a hiatus of exploration activity in Afghanistan largely on account of the security issues, for perhaps around 20 to 25 years.

The Russians in the mid-1970s did a considerable amount of work, but after the invasion and through the eighties, nineties and now in the first part of the century there hasn't been that much work done.

So there fore within the donor community there has been a great push to provide technical expertise to build capacity within the Afghan Ministry of Mines and Petroleum and within the Afghan Geological Survey to help the Afghans help them selves and to develop their mineral resources and to exploit those resources for profit.

" Afghanistan's Geological Survey team will have an opportunity to play a vital part in their country's economy.

Much hinges on a long-awaited mining law to be passed ensuring the country's resources are fairly and legally exploited.

Video Survey Mining for minerals in Afghanistan

Hydrometallurgy For Gold Leaching

Refiners hydrometallurgy will give examples of careers and precious metals using chemistry both inorganic and organic, chemical engineering, metallurgical engineering and others. Hydrometallurgy for gold refers the processing techniques that require wet chemistry approaches to separate the precious metals from the surrounding materials vs pyrometallurgy which requires heating and smelting operations to perform the separation.

Hydrometallurgy to take many forms depending on the substrate or the material which contains the precious metals. Many of these chemicals used are very hazardous and these processes should only be done by professional refiners

Hydrometallurgy is an extractive metallurgy process using aqueous solutions to recover metals it involves technologies with solubilize, concentrate and then recover specific metals.

For example a first step maybe to chemically dissolve or leach a material to eventually extract metals by means of precipitation or electrically reducing the metals.  Leaching is the first process used to extract metals into an aqueous solution, chemical acids or alkali eyes are used to convert metals into soluble salts within the solution.

For example aqua regia is a highly corrosive acid mixture of nitric and hydrochloric acids which will dissolve most metals, including gold platinum and paladium

In the other platinum group metals however do not dissolve in aqua regia so it can be used to separate these groups, all those silver also dissolves in aqua regia it immediately precipitates to silver chloride so does not go in the solution. Nitric acid alone is used to dissolve silver.

The different gold leaching processes are descriptively named :

Gold leaching processe

1. Situ Leaching

 In situ leaching also called  solution mining. Extrating the minerals directly from ore in the mining. Leach solutions are pumped through the ore to surface.  In situ leaching is occasionally used in select mining operations to leach precious metals from surrounding rock structures.

2. Heap leaching is routinely used to remove gold from ore deposits in tailings

3.Vat leaching is most frequently used when removing gold from secondary scrap materials such as electronic scrap or even jewelry scrap

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How To Work The Heap Leaching Mining  
Gold Leaching Process With Carbon In Pulp

4. Agitated leaching is where the material is saved in slurry with the extracting solution.

5. Pressure leaching places the material, solvent along autoclaves to pressurize heat, it is also used when gases need to be added for the leaching reaction.

The pressure oxidation process the free gold is an example of this cyanidation and chlorination are other pressure leaching processes, after leaching solution concentration and purification steps are employed to further concentrate and separate the precious metals

These refining processes can be used for precious metals extracted from primary remaining sources as well as secondary sources of industrial or recycle scrap materials

Video How To Refine Precious Metals - Hydrometallurgy