Presentation on theme: "BY OPAFUNSO, ZACHEUS OLANIYAN (MSc (Rapid City, USA), MBA (Vermillion, USA), PhD (Akure, Nigeria), FNSE, MNIM) PROFESSOR OF MINING ENGINEERING & AG. DEAN,"— Presentation transcript:
BY OPAFUNSO, ZACHEUS OLANIYAN (MSc (Rapid City, USA), MBA (Vermillion, USA), PhD (Akure, Nigeria), FNSE, MNIM) PROFESSOR OF MINING ENGINEERING & AG. DEAN, SCHOOL OF MANAGEMENT TECHNOLOGY (SMAT), THE FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE (FUTA), NIGERIA Overview of Best Practices and Field Experience in Artisanal and Small Scale Gold Mining in Nigeria
Abstract This paper presents an over-view of field experience in artisanal and Small Scale gold mining operations in Nigeria and recommends best practices for such activities to take care of the associated dangers and environmental effects. Current technical data on ASM gold mining operations such as manual breakage, washing and winning, panning, and mercury amalgamation methods were examined with a view to recommending international best practices for the industry.
Abstract Contd. Environmental effects of the use of mercury to recover gold from gangue were also discussed. The paper conclude that artisanal gold mining in Nigeria is ripe for a revolution that can lead to the birth of a modern and environmentally friendly method of mining for the benefits of ASM operators, the Governments and the communities where gold mining operations take place. Key words: Gold, Mercury, amalgamation, pollution, mining, operations, communition.
INTRODUCTION Definition of Artisanal and small-scale mining: -as mining activities that uses crude or rudimentary methods to extract and process minerals and metals on a small scale -it encompasses all small, medium, informal, legal and illegal miners who use rudimentary processes to extract minerals from secondary and primary ores.
Introduction contd Artisanal miners work in: *difficult and often very hazardous conditions *in the absence of the required safe mining knowledge or any regulations *or standards, toxic materials can be released into the environment, posing large health risks to the miners, their families and surrounding communities Thus, gold mining operations are particularly dangerous, as they often use the mercury amalgamation process to extract gold from ores.
Introduction contd Despite serious dangers occasion by this activity, artisanal gold mining operations continue to spread due to: * rise in the demand for gold * unattractive nature of other means of livelihoods such as farming in the areas where the mineral is substantially available. The environmental effects of artisanal gold mining activities, has spurred a number of environmental conscious organizations including United Nations to seek for alternative ways of recovering gold
Factors influencing participants in the vocation Lack of Organization and Instabilities of the miners Illiteracy Lack of technical assistance Lack of Financial assistance made available to the artisans Improper regulations guiding the operations of the miners poverty and unemployment;
Gold Occurrence and Mineralization in Nigeria Gold in Nigeria is found in alluvial/eluvial placers and primary veins from several parts of supracrustal (schist) belts in the Northwest and Southwest of Nigeria. The most important occurrences are found in the Maru, Anka, Malele, Malendo, Sofon Birnin Gwari-Kwaga, Gurrara, Bin Yauri, Okolom- Dogondaji, Ijero - Ekiti and Iperindo areas, all associated with the schist belts of Northwest and Southwest Nigeria. There are also a number of smaller occurrences beyond these major areas. (NGSA, 2010)
Location of Gold Occurrences in Nigeria (source: MMSD, 2010)
LocationState Geopolitical Zone MaruZamfara StateNorth West Zone AnkaZamfara StateNorth West Zone MaleleZamfara StateNorth West Zone Sofon Birnin Gwari Kaduna StateNorth West Zone MalendoKebbi StateNorth West Zone Bin YauriKebbi StateNorth West Zone GurraraNiger State North Central Zone Okolom - Dogondaji Kogi State North Central Zone Ipinrindo - Ilesa Osun StateSouth West Zone Ijero - EkitiEkiti StateSouth West Zone Table I: Locations of Gold Deposit in Nigeria
Major Areas of Gold Mineralization in Nigeria (Source: NGSA, 2010)
Statistics of Gold production in Nigeria (NGSA, 2010)
Gold Production is by Manual Method Typical Manual Washing Method The production of Gold in Nigeria has not been through mechanization methods of mining as a result of the nature of the deposit as highlighted above. Methods used for mining operations include: * crude methods of manual breakage to have access to the deposit. * washing and winning through panning, and *finally mercury amalgamation Field Experience in Small Scale Gold Mining in Nigeria
Stages in Mining of Gold Typical Amalgamation & Burning Process Breakage Communition Gravity Concentration Process Sluicing and Disposal Amalgamation and Burning Process Method of Recovering of Gold in Nigeria
Manual Breaking Communition The ASM operator uses manual method of breaking the rocks containing the Gold deposits to get lumps. This is then transfer into the communition section. During this stage, the operator engages his wife/wives and children to further break the lumps into smaller pieces using metallic mortar and pestle. ASM Methods of Gold Mining
Gravity Concentration Process This is done by mixing the pulverized ore with water and then allowing it to settle after agitation. Regular agitation takes place every day for about a week. The upper sediment is transferred to another tank and the same process is repeated. The lower sediment which is rich in Gold goes through the next stage of sluicing. ASM Methods of Gold Mining Contd
Sluicing and Disposal This is commonly done with a wooden sluice box. The ASM operator tilts the box in a small angle to allow the sand particle move in an upstream and a downstream manner. There is always a sieve at the intake section to prevent large particles from passing through the sluice box. Visible gold is picked out of the sluice box, amalgamated for the recovery of pure gold. ASM Methods of Gold Mining Contd
Amalgamation and Burning Process Artisanal gold miners combine mercury with gold- carrying silt to form a hardened amalgam that has picked up most of the gold metal from the silt The amalgam is later heated with blow torches or over an open flame to evaporate the mercury, leaving small gold pieces. The gaseous mercury is inhaled by the miners and often by their immediate family, including their children. Mercury that is not inhaled during the burning process often settles into the surrounding environment or circulates globally for future deposition far from the site
Amalgamation &Burning Process Contd The deposited mercury is absorbed by a variety of living organisms This transforms elemental mercury into methyl mercury Methyl mercury is one of the most dangerous neurotoxins that contaminate the food chain through bioaccumulation Ores recovered from alluvial deposits are also subjected to gravity concentration and the other processes follow suits.
Environmental Effects of Artisanal Gold Mining activities Gold mining activities have mainly been done through crude methods of mining with consequential hazards to the health of the miners, their respective families and the communities surrounding such mining activities. some environmental hazards of mining activities are: Mercury pollution: Water pollutions Landscape degradation Destruction of habitats Loss of organic soil Deforestation
Best Practices in ASM Gold Mining in Nigeria As a result of catastrophic event in Zamfara State last year which led to the death of over 400 children due to lead poisoning, the United Nations has recommended proper enlightment and training for the artisanal miners of Gold in the affected areas in Nigeria. This will enable them to know and adopt best internationally recognized practices for safe mining operations in their community.
Best Practices in ASM Gold Mining in Nigeria Contd Best practices in artisanal gold mining will be the method that will reduce the environmental pollution, health hazards occasion by the use of mercury in the recovery of Gold especially with the method of amalgamation. For the purpose of this presentation, we shall look at the best practices from three perspectives: Exploration Methods Exploitation Methods Processing Methods
Best Practices in ASM Gold Mining in Nigeria Contd Veiga (1997) suggested four different approaches to solve mercury problems, namely: Armed or Enforcement Approach: Legal Approach: Ecological Approach: Educational Approach:
Best Practices in ASM Gold Mining in Nigeria Contd technically, Veiga, (1997) suggested the following three solutions that can lead to mercury reduction: Search for alternative processes to avoid mercury Implement remedial procedures to highly polluted sites Apply measures to reduce mercury emissions
Best Practices in ASM Gold Mining in Nigeria Contd Telmer (2007) outlined four strategies that can lead to reduction of mercury use in Artisanal small scale gold mining to be: Introducing improved mining practices, including the elimination of whole ore amalgamation and open-air amalgam burning; Introducing Hg free processing where viable; An increased price for mercury; Awareness campaigns, policy and governance reforms, and community economic diversification
Strategic Plans to Introducing Mercury Free Method In other to have a mercury free method in artisanal gold mining in Nigeria, the following strategic plans that had worked in Brazil and Venezuela can be implemented in Nigeria: The International Guidelines on Mercury Management must be put in place; the effort put in by the organizer of todays Anglophone West Africa Regional Awareness-Raising Workshop on Mercury in Artisanal Small Scale Gold Mining is commendable. National Law on Mercury Management must also be formulated and implemented
Strategic Plans to Introducing Mercury Free Method Contd Promotion of Awareness and Compliance for Artisanal miners and their community is also recommended. The transfer of emerging technology for mercury free method of mining is desirable; however, it should be with effective training of end-users. The Federal Government of Nigeria need to formulate a law, if not already in place, that prevents importation or production of mercury
Strategic Plans to Introducing Mercury Free Method Contd The artisanal miners should be organized under a relevant cooperative society to enable them access microcredit loans and access government benefits The Federal Government of Nigeria need to formulate a law, if not already in place, that prevents importation or production of mercury These artisanal miners should be organized under a relevant cooperative society to enable them access microcredit loans and access government benefits This will enable them carry out safe and environmentally friendly mining operations.
Conclusion The paper conclude that artisanal gold mining in Nigeria can undergo a revolution that can lead to the birth of a modern and environmentally friendly method of mining for the benefits of ASM operators, the Governments and the communities where gold mining operations is taken place. In addition, with the conscious efforts of Federal government and State Governments in the gold mineral zones showing interest and soliciting for partnership with well meaning investors in gold mining, there is a good indication that gold mining in Nigeria is about to witness a revolution in the right direction.
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