Cyanide Use in Small-Scale Gold Mining in Tanzania: Safety, Regulation, and Sustainable Alternatives

In the rugged terrains of rural Tanzania, where the pursuit of gold fuels livelihoods and local economies, small-scale mining operations have increasingly turned to cyanide as a means of extracting precious metal from low-grade ore. While this method offers efficiency and accessibility to artisanal miners, the proliferation of informal cyanide use raises urgent concerns about environmental degradation, worker safety, and community health. Unregulated handling of this potent chemical has led to toxic spills, water contamination, and preventable fatalities, spotlighting a critical gap in oversight and enforcement. Despite established protocols under Tanzania’s mining regulations, implementation remains inconsistent, leaving vulnerable populations at risk. Yet, within this challenge lies an opportunity—scientists, policymakers, and local stakeholders are now collaborating to introduce safer, sustainable alternatives such as gravity concentration and non-toxic reagents. This evolving landscape underscores the pressing need to balance economic necessity with environmental stewardship and human well-being in Tanzania’s dynamic small-scale gold mining sector.

Understanding Cyanide Processing in Tanzanian Artisanal Gold Mining

• Cyanide processing in Tanzanian artisanal and small-scale gold mining (ASGM) involves the use of sodium cyanide to dissolve gold from ore through a chemical leaching process. Despite regulatory prohibitions, the practice persists due to its efficiency in extracting fine gold particles from low-grade ores, particularly in regions with limited access to alternative technologies.

• The process typically begins with manual ore crushing using hammers or rudimentary crushers, followed by grinding in ball mills or mortar and pestle setups. The finely ground material is then mixed with a dilute cyanide solution (usually 0.01–0.05% NaCN) in lined pits, barrels, or vats. Gold dissolves to form a soluble complex—dicyanoaurate (Au(CN)₂⁻)—which is later recovered via adsorption onto activated carbon or direct precipitation with zinc (Merrill-Crowe process). Final recovery often involves rudimentary smelting of loaded carbon or precipitates, conducted without emission controls.

• Environmental and health risks are significant. Open leaching setups result in uncontrolled cyanide discharge into soil and water bodies, posing acute toxicity risks to aquatic life and humans. Chronic exposure among miners occurs through dermal contact, inhalation of hydrogen cyanide gas (especially in acidic conditions), and contaminated water consumption. Fatalities from accidental ingestion or poor handling have been documented, underscoring the absence of protective equipment and training.

• Regulatory enforcement remains inconsistent. While Tanzania’s Mining Act and Environmental Management Act prohibit unlicensed use of hazardous chemicals, enforcement capacity at remote mining sites is limited. Many operations function informally, evading oversight. The National Environmental Management Council (NEMC) and Ministry of Minerals lack sufficient personnel and resources for monitoring ASGM zones, particularly in Geita, Nzega, and Shinyanga.

• Data on cyanide sourcing indicate informal supply chains, often diverted from licensed industrial mines or imported without customs clearance. This undermines traceability and accountability. Despite the government’s promotion of mercury-free initiatives, no formal cyanide management framework exists for ASGM, leaving a critical policy gap.

• Technological alternatives such as gravity concentration (e.g., centrifugal concentrators) and borax-assisted smelting offer safer, effective gold recovery without toxic reagents. However, adoption is hindered by capital costs, lack of technical training, and entrenched practices. Sustainable progress requires integrating formalization efforts with access to safer technologies and robust chemical management policies.

Regulatory Framework for Cyanide Use in Small-Scale Mining Operations

• Tanzania regulates cyanide use in mining under the Minerals Act, No. 14 of 2010 and its associated Minerals (Cyanide Management) Regulations, 2018, which align with the International Cyanide Management Code (ICMC). However, formal adoption of the full ICMC remains limited to large-scale operations; small-scale mining activities operate under a distinct, less stringent framework.

  

• Small-scale gold mining in Tanzania is primarily governed by the Small-Scale Mining Act, 1999, administered by the Ministry of Minerals. While this legislation provides general operational guidelines, it lacks specific provisions for cyanide handling, storage, transport, or waste management. This regulatory gap exacerbates risks associated with informal and unlicensed use of cyanide in artisanal and small-scale mining (ASM).

• The Tanzania Bureau of Standards (TBS) enforces quality standards for chemicals used in mining, including cyanide. Yet, enforcement in remote ASM sites remains weak due to limited monitoring capacity, inadequate training, and insufficient technical resources at the district level.

• Licensing for small-scale miners is managed through Mining Licenses (MLs) issued by Regional Mining Officers. However, these licenses do not mandate compliance with cyanide-specific safety protocols, nor do they require environmental impact assessments focused on cyanide use. Consequently, many operators employ rudimentary and hazardous methods such as bottle-roll leaching without containment or tailings management.

  

• Regulatory oversight is further fragmented across multiple agencies—the Ministry of Minerals, Ministry of Environment, and local government authorities—leading to coordination inefficiencies and inconsistent enforcement.

• In practice, most small-scale miners use cyanide without formal training or protective equipment. The absence of mandatory training programs on safe cyanide handling compounds health and environmental risks.

• Recent efforts by the government, supported by development partners, aim to formalize ASM operations and improve chemical safety through pilot programs promoting best practices. However, these initiatives remain localized and lack nationwide scalability.

• A critical need exists to integrate cyanide-specific regulations into the small-scale mining legal framework, enforce standardized handling procedures, mandate closed-loop systems, and establish accessible training and monitoring mechanisms. Without targeted regulatory reform, the use of cyanide in small-scale operations will continue to pose significant occupational, community, and environmental hazards.

Health and Environmental Risks of Cyanide in Rural Mining Communities

• Exposure to cyanide in rural mining communities poses significant health risks due to inadequate handling, storage, and lack of protective equipment. Acute cyanide poisoning can occur through inhalation, ingestion, or dermal contact, manifesting in symptoms such as headache, dizziness, nausea, respiratory failure, and, in severe cases, rapid death due to inhibition of cellular respiration.

• Chronic low-level exposure, though less immediately apparent, contributes to long-term neurological and thyroid dysfunction. Vulnerable populations, including women and children involved in or living near mining operations, face disproportionate risks, particularly where informal processing occurs within residential areas.

• Environmental contamination is pervasive in areas where cyanide is used without engineered containment systems. Tailings containing residual cyanide and metal-cyanide complexes are frequently discharged directly into soil and water bodies, leading to the degradation of aquatic ecosystems. Free cyanide is highly toxic to aquatic life, even at low concentrations, and can disrupt food chains and biodiversity.

• In Tanzania, many small-scale mining operations lack lined ponds or cyanide destruction systems, increasing the likelihood of groundwater infiltration and downstream contamination. Seasonal rainfall exacerbates the spread of pollutants, affecting agricultural soils and drinking water sources used by surrounding communities.

• Regulatory enforcement remains weak in remote areas, and miners often lack training on safe cyanide use. The absence of monitoring infrastructure prevents timely detection of contamination events. Additionally, cultural practices and economic necessity often outweigh awareness of risk, perpetuating unsafe handling.

• Sustainable risk reduction requires a multi-pronged approach: formalization of artisanal mining, implementation of closed-loop processing systems, community-based environmental monitoring, and access to safer alternative technologies such as gravity concentration or non-toxic leaching agents.

• Without systemic improvements in regulation, education, and infrastructure, cyanide use will continue to endanger both human health and ecological integrity in rural mining regions of Tanzania.

Best Practices for Safe Cyanide Management in Small-Scale Plants

• Implement engineering controls such as fully enclosed cyanide mixing and dosing systems to minimize operator exposure. Closed-loop systems reduce the risk of leaks and spills while ensuring consistent reagent delivery.

• Store sodium cyanide in a dedicated, well-ventilated, and secure storage area, elevated above ground level and protected from moisture, heat, and direct sunlight. Containers should remain sealed and labeled in compliance with national and international hazard communication standards.

• Conduct cyanide inventory tracking using a logbook or digital system to record receipt, usage, and disposal. Regular audits help prevent theft, diversion, and overuse, supporting both safety and regulatory compliance.

• Require all personnel handling cyanide to wear appropriate personal protective equipment (PPE), including chemical-resistant gloves, face shields, impermeable aprons, and respiratory protection where airborne exposure is possible. PPE must be inspected, cleaned, and replaced according to a documented maintenance schedule.

• Establish emergency response protocols, including immediate access to antidote kits (e.g., hydroxocobalamin), eyewash stations, and safety showers. All workers must be trained in first aid specific to cyanide exposure, and drills should be conducted quarterly.

• Design and operate tailings management facilities to prevent seepage and overflow. Lined impoundments with leak detection systems and secondary containment barriers significantly reduce environmental contamination risks. pH must be maintained above 10.5 in process solutions to minimize hydrogen cyanide (HCN) gas evolution.

• Monitor cyanide levels in process streams and effluents using reliable field test kits or portable analyzers. Results should inform operational adjustments and ensure compliance with Tanzania’s National Environmental Management Council (NEMC) discharge limits.

• Provide mandatory, recurrent training for all staff on cyanide hazards, safe handling procedures, emergency response, and environmental stewardship. Training records must be maintained and accessible for inspection.

• Decommission cyanide-related infrastructure responsibly at end-of-life by neutralizing residual cyanide using hydrogen peroxide or SO₂/air (INCO) methods, followed by verification testing to confirm detoxification.

Adherence to these practices mitigates health, safety, and environmental risks while aligning small-scale operations with international best practices, including those outlined in the International Cyanide Management Code.

Emerging Alternatives to Cyanide in Tanzania’s Gold Extraction Sector

• Thiosulfate leaching has emerged as a leading non-toxic alternative to cyanide in Tanzania’s gold extraction sector, particularly for ores containing high concentrations of copper or carbonaceous material that hinder cyanidation efficiency. Unlike cyanide, thiosulfate forms stable complexes with gold under alkaline conditions and poses significantly lower environmental and human health risks. Pilot-scale applications in selected artisanal and small-scale mining (ASM) operations in Geita and Nzega have demonstrated recovery rates exceeding 85%, with reduced reagent costs when recycled effectively.

• Another promising alternative is halide-based leaching, particularly iodine-iodide and bromine-bromide systems. These oxidizing systems offer rapid gold dissolution kinetics and operate effectively across a broad pH range. Their adoption remains limited due to higher reagent costs and logistical challenges in reagent supply, but localized production initiatives are being explored to improve feasibility for small operators.

• Bioleaching using chemolithotrophic bacteria such as Acidithiobacillus ferrooxidans has shown potential for pretreatment of refractory gold ores, enhancing gold liberation prior to non-cyanide extraction. While not a direct cyanide replacement, it complements alternative lixiviants by reducing the need for energy-intensive roasting or pressure oxidation.

Regulatory support and technical capacity building remain critical for scaling these technologies. The Tanzanian government, in collaboration with research institutions such as the University of Dar es Salaam and international development partners, has initiated demonstration projects to assess the economic viability and environmental footprint of these alternatives. Integration with existing gravity and flotation circuits further enhances their practicality for small-scale operations. Sustainable adoption will depend on accessible financing, localized technical training, and alignment with national mining safety and environmental standards.

Frequently Asked Questions

What are the regulatory requirements for operating a cyanide-based small-scale gold plant in Tanzania?

Small-scale gold processing plants in Tanzania using cyanide must comply with the Tanzanian Mining Act, Environmental Management Act, and guidelines from the President’s Office – Regional Administration and Local Government (PO-RALG). Operators require a valid environmental impact assessment (EIA) approval, cyanide handling certification, and must follow the International Cyanide Management Code (ICMC) principles, even though full certification is typically mandated only for large-scale mines. The Ministry of Minerals and the National Environment Management Council (NEMC) enforce compliance through site inspections and audits.

How is cyanide safely managed in artisanal and small-scale mining (ASM) operations in Tanzania?

Cyanide in Tanzanian ASM operations is managed through controlled reagent use, secure storage in locked, ventilated areas, and strict handling protocols. Best practices include using closed-system mixing to prevent exposure, real-time monitoring with cyanide test kits, and training miners in first aid and emergency response. The Tanzanian government, in partnership with initiatives like the World Bank’s Minamata project, promotes cyanide substitution alternatives and phased adoption of safer, contained technologies.

Are small-scale cyanidation plants legal in Tanzania?

Yes, small-scale cyanidation plants are legal in Tanzania under specific licensing and regulatory frameworks. Operators must obtain a Special Mining Licence (SML) or Primary Mining Licence (PML), register with the Barrick-Tanzania Mining Certification Program, and adhere to environmental and occupational safety standards. Unauthorized use of cyanide or non-compliant processing is subject to penalties, including plant shutdowns and revocation of licences.

What are the alternatives to cyanide in small-scale gold processing in Tanzania?

Non-cyanide alternatives include gravity concentration (e.g., shaking tables, centrifugal concentrators), mercury-free retorts, and newer technologies like thiosulfate or halogen-based leaching. The Tanzanian government promotes gravity methods under the National Artisanal and Small-Scale Mining Policy to reduce environmental risks. While these methods are less toxic, they may have lower recovery rates for refractory ores, making cyanide still prevalent despite hazards.

How does cyanide use in small-scale plants impact the environment in Tanzania?

Improper cyanide use in small-scale plants can lead to soil and water contamination, particularly in unlined tailings pits near rivers. Acute toxicity affects aquatic life and poses human health risks. The NEMC monitors water quality near mining zones and conducts audits. Experts emphasize mandatory lined leach pads, cyanide detoxification (e.g., SO2/air method), and zero-discharge tailings management to mitigate ecological damage.

What training programs exist for safe cyanide handling among small-scale miners in Tanzania?

The Tanzanian government collaborates with the Canadian International Resources and Development Institute (CIRDI), the Artisanal Gold Council (AGC), and the UNDP to deliver cyanide safety training. Modules cover personal protective equipment (PPE), chemical handling, spill response, and emergency procedures. Certified trainers deliver instruction through Mining Training Centres in Geita, Mwanza, and Shinyanga, with curricula aligned with international safety standards.

Can small-scale miners in Tanzania access the International Cyanide Management Code?

While full ICMC certification is intended for industrial-scale operations, small-scale miners in Tanzania can adopt its principles through localized frameworks like the Tanzanian Cyanide Best Practice Guidelines. The Ministry of Minerals promotes an adapted version focusing on secure storage, exposure control, training, and emergency planning. Third-party verification and incremental compliance are encouraged to improve safety without imposing undue financial burdens.

What are the recommended containment systems for cyanide tailings in Tanzanian small-scale plants?

Engineered containment systems include double-lined tailings ponds with leachate collection, impermeable HDPE liners, and regular leak detection. Tailings must undergo detoxification before storage, using hydrogen peroxide or natural degradation under controlled pH. Experts recommend centralized processing hubs to pool resources and ensure proper tailings management, reducing environmental liability for individual operators.

How is compliance with cyanide regulations monitored in Tanzanian small-scale mining?

The NEMC, Minerals Audit Department, and local mining officers conduct routine site inspections, document audits, and community whistleblowing programs. Satellite imagery and field testing kits help detect illegal discharges. Operators must maintain cyanide inventory logs and submit biannual environmental reports. Non-compliant sites face suspension, fines, or criminal charges under the Environmental Act.

What role do cooperatives play in improving cyanide safety in Tanzania?

Mining cooperatives enhance safety by pooling financial resources to invest in engineered processing plants, centralized tailings facilities, and professional training. Registered cooperatives gain access to government support, formalized markets, and technical assistance programs. They are instrumental in scaling up best practices and ensuring collective adherence to cyanide management protocols.

Is community involvement required in cyanide plant operations?

Yes, Environmental and Social Impact Assessments (ESIAs) require consultation with affected communities before plant licensing. Ongoing engagement includes public disclosure of monitoring data, emergency planning with local leaders, and establishing community liaison committees. Transparent communication builds trust and enables early detection of environmental concerns.

What technological upgrades are recommended for safer small-scale cyanidation in Tanzania?

Experts recommend transitioning from manual vat leaching to continuously monitored carbon-in-leach (CIL) or carbon-in-pulp (CIP) systems with automated dosing. Integration of IoT sensors for pH and cyanide concentration, along with solar-powered detoxification units, improves safety and efficiency. Partnerships with research institutions like the University of Dar es Salaam support technology pilot programs.