Projects
West Musgrave
The West Musgrave Project (WMP) is a greenfield copper and nickel project owned by OZ Minerals Limited (OZ Minerals), a fully owned subsidiary of BHP. The WMP is located approximately 1,300 km north-east of Perth, near the border of South Australia and Northern Territory. MBS Environmental were approached in 2018 during the early stages of the project. Since then, MBS have been heavily involved in implementing a broad range of services.
West Musgrave Assistance:
- Referral to the Western Australia Environmental Protection Authority under Part IV of the Environmental Protection Act 1986.
- Preparation of an Environmental Review Document under Part IV of the Environmental Protection Act 1986
- Development of a Section 45C and a change to the approved conditions of MS 1188 under Section 46 of the Environmental Protection Act 1986
- Strategic advice regarding the environmental approvals pathway and regulator consultation.
- Regulatory secondary approvals including Mining Proposals, Clearing Permits and Works Approvals and all subsequent revisions
- Preparation of a Mine Closure Plan in accordance with the Guidelines for Preparing Mine Closure Plans
- Regulator consultation and specialist environmental project development advice through all stages of the project
- Completion of the Compliance Assessment Report (CAR) for submission to the Department of Water and Environmental Regulation, Environmental Protection Authority Services
- Preparation and submission of the Annual Greenhouse Gas Report
- Ongoing monitoring and compliance reporting to meet tenement and environmental licence conditions including water and vegetation monitoring and biannual/annual reporting.
- Environmental management assistance including preparation of environmental management plans and compliance auditing.
- Soil, Waste and Tailings Characterisation studies
- Undertake baseline contamination assessments
- Geochemical modelling for the Babel pit lake and pit lake closure planning.
- Assisted in the transfer of knowledge and provision of operational continuity during periods of ownership transition.
Process Waste & Tailings Characterisation Case Study
In 2021, OZ Minerals was preparing a pilot plant to process West Musgrave Ni-Cu concentrate to produce Mixed Hydroxide Precipitate (MHP). MHP is a key ingredient/feed material for use in lithium battery manufacture.
MBS Environmental (MBS) was commissioned to undertake long-term geochemical studies on WMP waste flotation tailings material and the MHP waste tailings produced from a pilot MHP plant trial. The process would use WMP sulfide flotation nickel concentrate as feed material, with a mixture of the WMP and MHP tailings proposed to be co-disposed in the TSF. MBS conducted a full programme of works which followed on from previous work at WMP by MBS for waste rock and tailings characterisation, soil and landform assessment, geochemical pit lake modelling, groundwater investigations, baseline transport route assessment and approvals assistance. Works on the tailings characterisation included:
- Sample selection and discussions with Project Metallurgists.
- Static geochemical testing of the tailings materials and blends to determine their composition, chemical form and potential to generate acid or neutral metalliferous drainage conditions according to state, national and international procedures accepted by regulators.
- Sequential and specialised leach testing using different conditions to determine the relative chemical forms of soluble, weakly bound, exchangeable and iron/manganese oxyhydroxide bound fractions.
- Kinetic (column) testing on the tailings materials to establish long term leaching behaviour and geochemical risk to the shallow freshwater aquifer.
- Reporting and interpretation of all results including interactions occurring within blended tailings and discussions on management implications for tailings disposal design.
- Providing advice to OZ Minerals in designing and seeking approvals for the WMP to minimise environmental impact, by providing an assessment of the tailings geochemical properties based on static and kinetic testing and making recommendations regarding suitable management measures.
Babel Pit Lake Modelling
In 2022, MBS Environmental was engaged to undertake a refined geochemical model of the pit lake water quality in Babel pit post closure. This included two scenarios of in-pit metalliferous waste rock material disposal to understand the high level/key risks associated with dissolved contaminants (e.g. salts, metals, metalloids) in relation to sensitive ecological receptors and any future users of the pit lake to inform the West Musgrave Mine Closure Plan.
The areas MBS assisted in were:
- Identification of contaminants of potential concern (CoPCs- nickel, copper, sulfate) and key project risks in regards acid or neutral metalliferous drainage (AMD/NMD) for the project based on MBS earlier work in geochemical characterisation of all waste materials.
- Assessment of the suitability of existing data for subsequent pit lake modelling and identification of significant knowledge gaps and implications.
- Generation of the pre mining/upgradient hydrochemical source terms and incorporation of new terms for the closure model to revise solute balance and geochemical models.
- Undertake long term predictive geochemical modelling for the pit lake water integrating water
balance and solute mass balance models. - Revise existing Tier 1 risk assessment, based on the outcomes of the refined modelling approach that incorporates:
- Identification of potential sensitive receptors that may be affected by the quality of the
pit water at various stages of filling (e.g., bats and avifauna). - Tier 1 assessment of toxicological risks from an ecosystem-level function perspective and
risks associated with future land use.
- Identification of potential sensitive receptors that may be affected by the quality of the
