mercury

Chemical Precipitation on Mercury

The Chemical Precipitation on Mercury of the Gilmour – Young Process is a method that has been employed at the Santa Francisca Mine, Nicaragua. The ore contains a very large percentage of clay, the slimes amounting to 70 per cent, of the ore. The ore is crushed by a No. 5 Krupp ball mill through a 30-mesh sieve, and is charged into Boss pans, 4 feet in diameter, in 2-ton lots, with 100 gallons of water, so as to form a thick pulp. From two to six bottles of mercury are added, and circulation continued until the globules can be seen dispersed through the pulp, and then the required amount of cyanide. After running for two hours, 10 lbs. weight of mixed copper and zinc amalgam are added, and the pan run for four hours more. The gold is dissolved in the cyanide and precipitated by the zinc and copper, only 10 grains of gold per ton remaining in solution.

The pulp and solution are then discharged into a settler and diluted, and the mercury recovered in the ordinary way. The amalgam is used over again, and eventually a bullion 800 fine is obtained by retorting.

The power required for treating 50 tons per ….Read more

Laboratory Mercury Separator 

Laboratory Mercury Separator is extensively used to separate floured mercury or amalgam from the tailings of any amalgamating unit.

Pulp is fed into the tube through the funnel in the top, and water is forced in at the lower part of the tube, creating a sufficient up-current to overflow the sands out of the discharge outlet near the top. Mercury and amalgam are of sufficient specific gravity to drop down through the up-current of water and collect in the removable mercury flask at the base of the tube. Water pressure at the inlet is regulated by a valve and when it is correctly controlled, very accurate discrimination can be obtained.Laboratory Separator, Mercury

This mercury separator is also used for cleaning up amalgamated sands and concentrates, being quick and accurate. This unit can be made in commercial sizes for large placer, amalgamation mill, and dredge work.

Dimensions

Mercury

Mercury for use with amalgam plates and barrels, ball mills, clean-up pans, etc., can be furnished at the prevailing market price. Specially designed metal containers can be supplied in a number of convenient sizes. These metal containers avoid spillage and breakage and ….Read more

Leaching Mercury Sulfide

Hydrometallurgical methods have received increased attention for the treatment of many ores in recent years. Whereas, direct furnacing has been regarded as the standard process for mercury (cinnabar) ores, hydrometallurgical methods offer an alternate consideration. The chemistry of this process is not new, but with the impetus to hydrometallurgical methods, it is only logical that this method should receive increased attention. The process parallels cyanidation for the recovery of gold and silver in many ways. The mercury sulfide (cinnabar) is dissolved in a sodium sulfide-sodium hydroxide solution and washed from the solids using counter-current decantation. The mercury is precipitated from solution using metallic aluminum.

An important contribution to the advancement of leaching practices for mercury ores is Report 5 entitled “Studies in the Hydrometallurgy of Mercury Sulfide Ores” by John N. Butler and published by the Nevada Bureau of Mines, Reno, Nevada. This report, here below, is an excellent reference.

Mercury Sulfide Leaching Leaching Mercury

The flowsheet in this study represents a condensed presentation of the process and is intended only to illustrate the general features of the treatment steps. Extensive testing should precede any plant installation.

The Mercury Leaching Process Flowsheet

CRUSHING – ….Read more

Mercury Ore Processing

The concentration of low grade cinnabar, HgS, with a specific gravity of 8.0-8.2 is effectively accomplished by gravity and flotation methods.

Cinnabar ores of relatively high mercury content can be retorted directly to expel the sulphur and condense metallic mercury, but for lower grade ores, preliminary concentration is advisable to reduce the tonnage for retorting.

Retorting and recovery of metallic mercury is widely practiced at small or large tonnage mines. Cinnabar decomposes, yielding mercury at a temperature from 500 to 600°C. The ore in question is assumed to contain cinnabar associated with a siliceous gangue. Grinding to minus 48 mesh is the economic liberation point, but considerable free cinnabar is released at about 10 mesh and warrants concentrating the mineral as soon as it is freed.

extraction of mercury from earth

A Mercury Ore Beneficiation Process Flowsheet

Crushing Circuit

Conventional single stage crushing comprises this section, since the tonnage is less than 100 tons per day. The mine ore is fed from the coarse bin by means of a Apron Feeder to the Jaw Crusher. Crusher feed passes over a grizzly with an opening similar to the crusher setting. Grizzly undersize and crusher discharge product are delivered to the fine ….Read more

Gravity Borax Method GBM Mercury Free Gold Recovery

Borax_Method_of_Gold Recoverymercury_kidThe Gravity-Borax Method GBM is still unknown  to most Artisanal and small-scale gold miners (ASGMs) worldwide as most still use mercury to extract gold. “Whole-ore amalgamation” is a technique that requires the use of 10–25 g of mercury to produce 1 g of gold. Within the last eight years, it has become evident that this technique is more widely used than earlier anticipated, and artisanal small-scale gold mining (ASGM) is now considered the single largest contributor to global mercury pollution with the environmental release of 2,000,000 lbs of mercury per year. The United Nations Environment Programme has estimated that ASGM contributes a 37% share of the anthropogenic emission of mercury to the atmosphere.

Whole-ore amalgamation is commonly practiced in the Philippines. The ore is mixed with water and crushed in a rod mill (a rotating drum with metal rods inside), after which mercury is added and milled with the ore. The gold dissolves in the mercury and forms amalgam. After the milling, the content is poured into a tub where the mercury (holding the gold) ….Read more

Illegal mercury used in small-scale gold mining damages Indonesian lands

Puncak area, West Java Wikimedia Puncak area, West Java
Wikimedia

Many developed nations hope 2014 can finally be the year when a real fight against the use of mercury in gold mining across the world starts. However, until then, several countries like Indonesia will continue to suffer the consequences of this and other dangerous techniques.

The small-scale, and many times illegal, gold mining operations spread across the country are responsible for the contamination of the local soil, water and air. They are equally responsible for the damages inflicted to the health of the miners, some of them very young children without any other choice.

The New York Times recently told the world how these small and apparently harmless operations run in Indonesia. They used the example of a young 15-year-old worker named David Mario Chandra to kick-off their story, saying how gold mining is changing the face of places like the remote mountains of West Java.

A workshop next to his family’s house in Cisitu, in Banten Province, contains machinery that turns gold ore into usable nuggets. The procedure seems simple enough: The crushed ore ….Read more

Children in the Philippines are damaging their health while mining for gold

399px-thumbnailThere are currently 115 million children with ages from five to 17 years old who work in hazardous occupations worldwide, the United Nations International Labor Organization estimates. Among them, about a million children work in the mining industry. Hundreds of maybe even thousands of them live in the Philippines.

Recently, the Center for Investigative Reporting, in collaboration with the Pulitzer Center on Crisis Reporting, published an article about this scourge through the site Philly.com. The piece started by telling the story of a young miner:

Romnick Bocejo picked up his blowtorch and blasted a small lump of mercury and gold. A cloud of toxic fumes rose around his head as the heat vaporized the mercury. He covered his mouth and nose with his T-shirt, and kept working.

At 16, Bocejo has worked half his life in the meager family business: looking for gold in the remote mining region of Camarines Norte, about 200 miles southeast of Manila.

One of his jobs is to burn the mercury, and on this occasion, he produced a button-size lump of nearly pure gold. He is uncertain whether to believe the smoke is dangerous.

….Read more

Signatories of the Minamata Convention [infographic]

A document that means “the beginning of the end of mercury as a threat to human health and the environment”. These were the words chosen by the executive director of the UN Environment Programme, Achim Steiner, to describe the Minamata Convention, recently signed by more than 90 countries.

These nations vowed to ban several mercury products until 2020 and are planning the best way to forbid the mining of fresh mercury and mercury emissions from new power plants, measures that must be applied within 15 years of the treaty coming into effect. Besides, the signatories will also have to eradicate or transform artisanal and small-scale gold mining operations that use mercury.

Overall, it’s an extremely important document for the future of the planet and that is why today we bring you this infographic that gathers all the signatories of the convention for you to see.

MinimataSignatoriesEdit-03

92 Countries sign anti-mercury treaty

751px-Hg_MercuryJapan hosted, earlier this month, the subscription ceremony of a groundbreaking global treaty to reduce mercury pollution. The Minamata Convention, signed by 92 countries, spells “the beginning of the end of mercury as a threat to human health and the environment”, said Achim Steiner, executive director of the UN Environment Programme (UNEP), the site All Africa reports.

Now that the treaty is signed, there’s still a lot of work to do in order to provide the necessary funding and technical advice needed to implement the anti-mercury measures, expanding the monitoring capacity worldwide. The Minamata Convention treaty will come into force once 50 countries have ratified it.

Tim Kasten, deputy director of UNEP’s Division of Environmental Policy Implementation, told SciDev.Net that:

We’re hoping that it will take a maximum of three years for ratification and that we will have early ratification based on the overwhelming support we have seen here, with 92 signatories and 139 countries in attendance.

The document proposes the ban of several mercury products by 2020 and plans to forbid the mining of fresh mercury and mercury emissions from new power plants within 15 years of the treaty coming into ….Read more

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