Learning and Discussion of Innovative ideas about Mining Waste Management and also Mining Related News and Activities

  • Mine Waste Management Training

    Mine Waste Management Short training sponsored by Government of Japan through JICA in corporation with the Government of PNG through CEPA, MRA and DMPGM.

  • Mount Sinivit Mine

    Acid mine drainage (AMD) continues to flow from the abondoned workings (mine). It is of two types and they are Mine Drainage from underground and open-pit and the seepage water from waste dump and tailings dam.

  • Mining Warden Hearing at Ok Isai Village, Frieda River, East Sepik Province, PNG

    Landowner grievances is always a challenge for the PNG Mining Industry. However, the Regulators of the Mining Inductry facilitate Mining Warden Hearings and Development Forums to address grievances related to mining.

  • Osarizawa Underground Mine Adit

    Osarizawa Underground Mine is an abandoned mine in Akita Prefecture, Japan. Event though the mine is closed, the mine site is kept for sightseeing purposes.

  • Hidden Valley Tailings Storage Facility (TSF)

    Mine Waste refers to the waste related to mining activities such as tailings and waste rock. Management refer to how the mine derived waste is managed by the operator and or the Regulatory Body.




Showing posts with label Safe Handling of Mercury. Show all posts
Showing posts with label Safe Handling of Mercury. Show all posts

Wednesday, 14 February 2018

Environmental Impacts of Artisanal and Small Scale Gold Mining in Papua New Guinea


Mechanize Small Scale Mining

Artisanal and small scale gold mining (ASSM) offers lucrative employment opportunities to the locals of most developing countries. The major drawback of ASSM is its impacts on the environment as a result of improper mining and processing techniques. Exposed and disturbed lands are usually subject to soil erosion and avalanches of debris in active ASSM areas. Mercury is commonly used to concentrate gold, and if not handled properly causes pollution of life supporting river systems.

Small scale gold miners in many developing countries rely primarily on deposits containing free gold and may be classified as shallow/deep alluvial or lode type. The mining method used in artisan small scale gold mining employ very basic technology. Shallow alluvial deposits are commonly found in valleys and streams at depths not more than two meters. Deep alluvial deposits are found along major riverbanks and older river courses, and usually at depths exceeding six metres along the banks of rivers. The lode type of gold deposits is usually composed of partially weathered gold bearing reefs, which are either outcrops or near surface deposits. In Papua New Guinea, active artisanal mining are commonly found abandoned mining areas like Panguna and Missima and also near operating mines like Porgera, Eddie Creek in Wau Bulolo, Morobe Province. Not only that but also other parts of the Provinces also have active small scale miners. Other provinces include but not limited to: East Sepik, Sandaun, Enga, Western, Eastern Highlands, Jiwaka, Madang, Western Highlands, Oro, Milne Bay,Morobe.

 The small scale gold fields are mainly riverine deposits where mining occurs along river banks, terraces and in active river channels. Using poorly constructed sluice boxes, gold bearing material is fed into the inclined sluice boxes. The box is constructed using plywood or flattened roofing iron with wooden/metal ripples. These types of operations are associated with low to very low recovery because of uncontrollable river flow rates, incorrect inclination of the sluice boxes and inappropriate amounts of feed material at any one time. It is extremely difficult to introduce mechanised alluvial mining because of low skills and knowledge, isolation from transport infrastructure and lack of basic infrastructure.

The gold bearing gravels are concentrated by rippled sluice boxes. The fine gold is not commonly trapped in the ripple compartments. The fine particles of sand with gold in it are than poured into the panning dish for further panning. Mercury is placed in into the panning dish to concentrate the fine gold particles. Amalgamation is an efficient mean of extracting gold particles from concentrates after panning or sluicing.

In PNG small scale mining operations, the concentrates from sluicing operations are mixed with mercury in gold dishes or in sluice boxes. Mechanised concentrating equipment like the shaking table and Nelson concentrators are other options that few small scale miners are looking at. 

Health and environmental impacts (Watch Video)

The artisanal and small scale gold mining provides employment at local and national levels, and the sector is an important source for the inflow of foreign exchange into rural communities. However, small scale mining activities are associated with sensitive health and environmental issues.

The process of recovering gold by retorting and heating the amalgam over an open fire is a dangerous practice. The open fire could be in houses or at river banks and thus a whole family could be exposed to poisonous mercury fumes.

Concentrate from sluicing near streams is usually mixed with mercury and a considerable amount of mercury is lost to the streams. Apart from direct inhaling of mercury fumes by miners, aquatic life also feeds on mercury lost into the river, which are then eaten by the locals through the food chain. The Watut and Bulolo Rivers has been subject to prolonged mercury contamination and discharges of hydrocarbon wastes. The Watut people depend on the river for fishing, washing and farming on the river banks.

Some miners in old shafts and adits and they are consequently exposed to the trapped noxious gases such H2S. Locals have been reported that they are buried alive when they burrow through soft oxidized lodes or vein systems.

Some operators locate their sluice boxes in streams, thus polluting the water. Silting and stream discolouration are very common. Farmlands are usually destroyed by mining activities. Locals even uproot big trees along structurally defined thin gold deposits. Sometimes, the narrow gullies are not rehabilitated and are left to be taken care of by nature.

Exposed and disturbed lands are subject to soil creep widening the flow channels, and debris avalanches are common along rivers at the active mining areas. The loss of fertile land due to small scale mining puts socio-economic pressure on the local society. Old gravel pits are usually abandoned without reafforestation. Pits filled with stagnant water are common.

Education and training

Small-scale mining technology in most developing countries is simple and attracts many unskilled people. The desire for economic and social survival has attracted many people to the industry. The law expects the licensed small-scale miner to mine using effective and efficient methods, and observe good mining practices, health and safety and protect the environment.

The Small Scale Mining Branch of PNG Mineral Resources Authority (Formerly Department of Mining) in Wau, Morobe Provine has created education and training materials for the miners. The Department has produced seven booklets and DVDs on

• Simple Gold Mining;
• Basic Mining Practice;
• Advanced Mining practice;
• Handling of Mercury;
• Occupational Health and Safety;
• Environmental Issues; and
• Economics of Mining.

The major focus of the training resources is to ensure that small scale operations are safe, environmentally friendly and economically viable.

Small-scale mining operations in most developing countries have serious negative environmental impacts. One of the major factors is the implementation of the associated mining Acts  which are lacking.


Donor agencies like the World Bank, European Union and Japanese International Cooperation Agency (JICA) have in recent times shown keen interest in the negative and positive impacts of the PNG’s ASSM sector. AusAid and the World Bank have sponsored the building of the ASSM sector capability in PNG through legislative framework and training and awareness on the use of mercury.

Note: This article is a reproduction of a learning material with inclusion of up to date information.

Reference
[1] Ail, K. K. (2005. Kwoe River Alluvial Gold Deposit Evaluation and Development Plan, PNG University of Technology, Lae.

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Monday, 1 May 2017

Mercury Pollution and Prevention Measures In Papua New Guinea

Mercury is a heavy silvery-white liquid metal used in some thermometers and barometers. (Symbol: Hg). It is also used to extract fine gold from the mixture of fine sand. Dispose of mercury into the environment is harmful.

Mercury is used in many ways and people do not realize when it gets released into the environment which in turn causes mercury pollution.

In Papua New Guinea almost all Small Scale Miners use mercury in the amalgamation process during gold recovery from the fine sands. Mercury is used in different ways to recover gold. some pour in between the riffles on the sluice boxes in an attempt to capture fine-grained gold.

The contact time between the gold and mercury is not effective for the amalgamation to occur. Often fine gold remains suspended in the flow of particles above the riffles and do not settles to contact the mercury. Thus, about 30  percent (%) of mercury used in sluice boxes in PNG is release into the river systems.This is actually a treat to the environment.

The Mineral Resources Authority's Small Scale Mining Branch in Wau- Morobe Province try its best to train local miners especially small scale miners on Safe Use and Handling Of Mercury in the process of amalgamation. The Training Center also train the miners other alternatives to be use in the gold recovery process to avoid use of mercury.

Other alternative methods of gold recovery techniques the small scale miners should be looking at would be Gravity Separation methods in the recovery of fine gold.
Gravity separation methods are vital and best alternatives to engaged instead of Mercury. Such methods include but not limited to:

  •  Recovery of Fined Size of gold grain should use Shaking table, Humphreys spiral, Pinced sluices, Reichert cone, etc..
  •  Recovery of more finer gold particle should use Nelson concentrator, Falcon concentrator.
The mercury released into the environment is unaccounted for and undetected. Mercury can be detected by a Rapid Pack-test by use of Rapid pack test kits. However, rapid pack test is not available in the country and it is anticipated that pack-test kits will be imported from overseas to use for training and study purposes. 

The next strategy is to ban import of mercury and introduce the alternative gold recovery methods and draft a treatment strategy through research and training. 
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Osarizawa Mine in Akita Prefecture, Japan

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