Mercury pollution from artisanal gold mining in block B, El Callao, Bolívar State, Venezuela

Abstract

Artisanal and small-scale gold mining (ASM) is an essential activity in many developing countries. The current number of artisanal gold miners is estimated to be between 10 and 15 million people worldwide (Veiga and Baker, 2004) with almost 30% of this contingent being women (Hinton et al, 2003). Since 1998, annual gold production from ASM has constituted 20 to 30% of the global production, ranging from 500 to 800 tonnes (UNEP, 2002; MMSD, 2002). Assuming that miners lose between 1 and 2 grams of Hg per gram of gold produced, it is estimated that annually between 650 and 1000 tonnes of Hg are released into the environment. The predominant source of ASM Hg release is China (200 to 250 tonnes/yr) followed by Indonesia which releases 100 to 150 tonnes/yr, while Brazil, Bolivia, Colombia, Peru, Philippines, Venezuela and Zimbabwe each release from 10 to 30 tonnes/yr of Hg (Gunson and Veiga, 2004; Shoko and Veiga, 2003; Veiga, 2003; Veiga and Hinton, 2002). Mercury releases in Latin America are declining, as the most easily extractable ore has been depleted and the operating costs have increased. However, the gradual increase in the price of gold in 2003 is motivating miners to re-work abandoned ore deposits. The southern part of Venezuela below the Orinoco River, involving the State of Bolívar, the State of Amazonas, and the Federal Territory of Delta Amacuro, is called the Guayana Region. The main mining activities are conducted in the State of Bolívar, which has an area of 240,528 km2, comprising 75% of the hydroelectric potential of the country. Less than 5% of the Venezuelan population (which is 24.2 million) lives in the Guyana Region. In 1999, the labor force experienced a 1.1% decrease in number resulting in an unemployment rate of 13.2% (1,365,752 people). In 2000, 63% of the individuals making up the workforce were men. Unemployment among men reached 12.5%, 1.1% higher than 1999. In 2000, 14.4% of women did not have a job. This was 1.7% higher than in 1999 (CONAPRI, 2003). El Callao is located in the Northeastern part of the State of Bolívar, 150 km from Ciudad Guayana (Puerto Ordaz). Mining started in 1724, when Capuchin priests explored the area. (figure presented) The municipality of El Callao was founded in 1853 with the name of Caratal and many small gold mining companies were installed in the region. In 1970, CVG (Corporacion Venezoelana de Guayana) incorporated Minerven, a state-owned company, which currently has two cyanidation plants producing together approximately 200 to 300 kg of gold/month: the Peru Plant processes 5,200 tonnes of material/month and the Caratal Plant processes 14,000 tonnes/month. About 15% of the Peru Plant material is Hgcontaminated tailings purchased by the company from the artisanal gold miners. CVG-Minerven owns a total area of 48,848 ha of mining concessions. The company granted 77 concessions of mining of which 59 are contracts with companies and 18 with individuals. The main portion of CVG-Minerven mining concessions "rented" to third parties is named "Block B" (Figure 1). With an area of 1,785 ha, this site was chosen by UNDDO for this project. CVG-Minerven has also rented mining areas in Block B to organized companies (e.g. the American company Hecla Mine). In the State of Bolívar, with a population of 1,214,486, there are about 15,000 people directly involved in ASM. This includes about 2000 "bateeros" and "suruqueros" who are those miners using pans to extract gold and diamonds from alluvial deposits and tailings, 5,000 miners using hydraulic monitors in elluvial and colluvial operations (gold and diamond), 3,000 miners working-in hard rocks (quartz veins) and 5,000 miners operating in dredges and rafts in waterways all over the state. In Venezuela, two hundred and fifty years after the beginning of (the paper says mining started in 1724) mining activities, the social and economic situation of the artisanal miners has not changed substantially. Observations of small gold miners in the State of Bolívar, Venezuela, reveal serious effects on families as well as the degradation of the community's socioeconomic conditions. In El Callao, ASM miners mostly work in the CVG-Minerven concessions but there are also some illegal miners working outside these concessions. This has been generating employment for the surrounding communities. Since the gold ore is abundant and extremely rich, people rarely consider other types of economic activity. The ASM miners, to some extent, have played the role of gold prospectors for the company. As the price of gold has been increasing since the end of 2002, the number of ASM miners has increased substantially in the region and many of them are outsiders who have never had any previous experience in mining. Since 1995, UNIDO has provided technical assistance related to mercury pollution for government, companies and artisanal gold miners in Bolívar State, Venezuela. The situation, as reported by UNIDO (1996), was extremely serious in El Callao with miners and millers indiscriminately using mercury to amalgamate gold. The current work was conducted at the end of 2003 as a preliminary mission to assess the current health situation and to prepare for a more substantial project to be conducted in the future. The mission assessed the level of mercury intoxication of the miners and the surrounding population and introduced simple mineral processing techniques capable of substantially reducing mercury exposure and release in the region.