Tailings are the resulting material from finely-ground processed ore bearing rock that has been through several sizing, grinding, and processing steps. Tailings are processed and stored in tailings storage facilities (TSFs) to control safety and environmental risks. We give priority to the safety and integrity of TSFs. We implement a lifecycle TSF management and strategy to realize our commitment to responsible, environment-friendly, and sustainable mining development. It also includes the comprehensive utilization of tailings and the post-closure rehabilitation.
We follow the Global Industry Standard for Tailings Management comply with the Work Safety Law of the People’s Republic of China, the Mine Safety Law of the People's Republic Of China, the Safety regulations for tailings pond of China, the Code for construction and acceptance of tailings disposal facilities (GB50864-2013) the Provisions on Safety Supervision and Management of Tailings, and standards and regulations of the country in which we operate. We constantly strengthen our lifecycle TSF management in accordance with the highest safety requirements, meanwhile improving our standardized and systematic management methods. We also focus on the stability and drainage system of the TSFs. We will conduct risk evaluations, preventive maintenance and periodic reviews to ensure the safety and integrity of TSFs.
We implement our TSF safety management with a group-wide accountability requirements and professional teams. We promote the standardization of TSF safety management and emergency preparedness in order to minimizing incidents in the lifecycle of TSFs as much as possible.
On the premise of complying with local laws and regulations, we strive to avoid riverine tailings disposal and submarine tailings disposal principally. For the Porgera mine, we will discuss solutions with Barrick and further reduce or eliminate the number of tailings deposited in the river with a view to ultimately stopping all deposition.
PRINCIPLE 1: Respect the rights of project-affected people and meaningfully engage them at all phases of the tailings facility lifecycle, including closure
PRINCIPLE 2: Develop and maintain an interdisciplinary knowledge base to support safe tailings management throughout the tailings facility lifecycle, including closure
PRINCIPLE 3: Use all elements of the knowledge base - social, environmental, local economic and technical - to inform decisions throughout the tailings facility lifecycle, including closure
PRINCIPLE 4: Develop plans and design criteria for the tailings facility to minimise risk for all phases of its lifecycle, including closure and post closure
PRINCIPLE 5: Develop a robust design that integrates the knowledge base and minimises the risk of failure to people and the environment for all phases of the tailings facility lifecycle, including closure and post-closure
PRINCIPLE 6: Plan, build and operate the tailings facility to manage risk at all phases of the tailings facility lifecycle, including closure and post-closure
PRINCIPLE 7: Design, implement and operate monitoring systems to manage risk at all phases of the facility lifecycle, including closure
PRINCIPLE 8: Establish policies, systems and accountabilities to support the safety and integrity of the tailings facility
PRINCIPLE 9: Appoint and empower an Engineer of Record
PRINCIPLE 10: Establish and implement levels of review as part of a strong quality and risk management system for all phases of the tailings facility lifecycle, including closure
PRINCIPLE 11: Develop an organisational culture that promotes learning, communication and early problem recognition
PRINCIPLE 12: Establish a process for reporting and addressing concerns and implement whistleblower protections
PRINCIPLE 13: Prepare for emergency response to tailings facility failures
PRINCIPLE 14: Prepare for long term recovery in the event of catastrophic failure
PRINCIPLE 15: Publicly disclose and provide access to information about the tailings facility to support public accountability.
Every TSF construction project must have OHS facilities and environmental protection facilities, which are designed, constructed, and put into production with the main project at the same time.
Before the design and construction of TSFs, we will fully analyze the project location and conduct geotechnical engineering investigation. The design and construction must strictly comply with compulsory safety regulations and requirements to guarantee the project quality. We will stimulate credible failure scenarios throughout the TSF lifecycle to review the dam stability, drainage system, and monitoring facilities. Our TSF design and construction requirements include:
● Conduct feasibility study and safety pre-evaluation, and geotechnical engineering investigation before TSF construction, in order to evaluate potential safety risks and mitigations
● Set the stockpile method and the dam construction method based on hydrological and geological conditions in the mine site; and conduct stability analysis on landslide design and seismic design of TSFs
● Implement flood control design of the highest standard based on the climatic and hydrological conditions, such as rainfall and catchment area; and ensure that drainage facilities meet requirements
● Design and construct safety monitoring facilities; combine manual monitoring and online monitoring; and set relevant operational requirements of the monitoring facilities
● Construct TSFs in accordance with the design and construction plan strictly; establish a comprehensive quality and safety management system; properly arrange and organize the project construction; and carry out project inspection and acceptance with a specific focus on concealed works for the safety quality assurance
● Perform dynamic monitoring of tailings facilities and reliability analysis of communication equipment configuration
● Clarify land reclamation, future land use and post-closure matters
● Establish safety and environmental management system for TSFs
During the operation of TSFs, we set detailed operation plans on the quarterly and annual basis. We will focus on the indicator monitoring of tailings, damming and discharge, flood loading control, seepage control and seismic design, and conduct safety evaluation and review. Meanwhile, we will conduct monitoring and inspection to identify, control and reduce safety risks and potential hazards.
The safety monitoring system in every TSFs combines manual and online monitoring. The system regularly monitors the length of embankment, phreatic line and dam displacement.
Our operation inspection focuses on:
● Safety inspection of TSFs: including contour, size, deformation, displacement, cracks, landslides, phreatic line, infiltration, etc.
● Safety inspection of drainage structures: including deformation, displacement, break, clogging, and drainage capability.
● Safety inspection of surrounding areas: including the stability of surrounding mountains and dangerous behaviors such as illegal construction, operation, tailings reuse, water withdrawal, waste discharge, grazing and reclamation.
● Safety inspection of flood design: Conduct flood calculation before flood season every year and set flood control plans. Ensure that TSF indicators accord with the requirements. Carry out an emergency drill before flood season. Conduct regular quality inspection of drainage structure.
● Safety inspection of Seepage design: Monitor infiltration, seepage, swampiness of TSFs. Observe and record the phreatic line during the operation of TSFs. Take measures and add seepage facilities when the phreatic line exceeds the threshold.
● Safety inspection of seismic design: Conduct daily safety inspection and reinforce TSFs according to the highest TSF seismic design standards. Set emergency preparedness plans. Before earthquake, pay attention to the stability of embankment and prevent landslide. After the earthquake, emergency plans should be launched to comprehensively inspect the dam, drainage structure and flood control design. The damaged facilities should be repaired in time.
● The closure of TSFs includes safety evaluation, closure design & construction, and safety acceptance.
● If the tailings run to the final design elevation or stop discharging, the closure procedures shall be performed according to the relevant requirements.
● 12 months before the tailings reaching the designed final elevation, a qualified agency should be hired to evaluate the safety status and design the tailings closure. The safety evaluation report of tailing closure should systematically analyze the safety status of TSFs, and the design plan of TSF closure should include risk evaluation and mitigation measures.
● TSF closure design should be reviewed and approved by the safety production supervision and administration department. Tailings dams and design should be regulated strictly according to the TSF closure requirements.
● After completion of closure construction, a qualified agency should be entrusted to carry out safety evaluation and organize the safety acceptance of TSF closure.
● TSFs after closure is not allowed to store water without verification and approval. Daily maintenance and management of dam and flood discharge facilities shall be carried out according to requirements of closure management.
Metal ore may contain sulphide, and the waste rock and tailings containing sulphide will undergo a series of physical, chemical and biochemical reactions such as weathering, leaching, oxidation and hydrolysis under the action of air, water and microorganisms, thereby forming acidic wastewater with sulphuric acid.
We assess mine sites that have acid rock drainage risks and develop methods to reduce the generation of such drainage based on the Global Acid Rock Wastewater Guidelines. We incorporate acid rock drainage into our overall water recycling system, recovering valuable metals from higher concentration acid rock drainage, and then neutralising it with lower concentration acid rock drainage and reusing or discharging it after the required standards are met.