Brukunga Mine Site Notes for Visitors The township of Brukunga Technical management for budgets, planning, projects, water monitoring and The township of Brukunga is located 5 km reporting to the Environment Protection north east of Nairne and 40 km east of Authority (EPA) is provided from DMITRE Adelaide in the Mt Lofty Ranges. The town Adelaide office based staff. has approximately 220 people and 72 houses, now almost all privately owned. The annual budget for site operations is It was built in 1952 by the Government in the order of $750,000 per annum. The housing trust for rent to the Mine property has an area of 123 hectares november 2012 employees. and requires continuing maintenance of fences, firebreaks, noxious weeds and other pests, roads, stormwater drains, Site management landscaping and tree planting. The South Australian Government took responsibility for the site in 1977. The former Engineering and Water Supply Historic setting for Department (later SA Water) operated the Brukunga Brukunga site from 1980 to 1997. In 1998 The historic Brukunga Mine was operational responsibilities transferred established in the 1950s as a source to the Department of Primary Industries of sulphur to be converted to sulphuric and Resources South Australia (PIRSA) acid for use in the manufacture of and is presently with the Resources superphosphate fertiliser. Australian and Energy Group of the Department soils tend to be of a poor quality requiring of Manufacturing, Innovation, Trade, applications of fertiliser to sustain Resources and Energy (DMITRE). cultivated crops. Two dedicated full-time staff manage the When the Mine was constructed in the treatment plant and maintain the mine 1950s the world was rebuilding after World property. A range of short-term contractors War II and there was a great shortage of are used for specialty tasks including all materials. electrical, vehicle maintenance and plant, preventative and breakdown maintenance. 1 of 9 Department for Manufacturing, www.minerals.dmitre.sa.gov.au/brukunga Innovation, Trade, Resources and Energy Notes for Visitors Brukunga Mine Site Australia realised it was isolated from the To encourage mining of pyrite for UK and it became policy to become self- production of sulphuric acid the sufficient, increase the population and Commonwealth paid a bounty via the november 2012 develop regional areas. Assistance was Sulphuric Acid Bounty Act, 1954 and the offered to pay for immigrants to come to Pyrites Bounty Act, 1960. Only two mines Australia to clear and develop the land were established in Australia specifically and increase agricultural production. to mine pyrite ore, these being Brukunga and the King Mine at Norseman, Western Australia. In the late 1960s cheaper Mining at Brukunga sources of sulphur became available The development of Brukunga Mine was mainly due to Canada’s refining of ‘sour encouraged and sponsored by both the natural gas’. The government withdrew the State and Commonwealth Governments pyrite subsidy on 31 May 1972 and both as part of the drive for self-sufficiency and pyrite mines ceased mining operations on full employment. The State Government the same day. fostered the formation of the company, Nairne Pyrites Pty Ltd, a consortium of three fertiliser manufacturers and a mine After mine closure operator: Cresco Fertilisers, Adelaide Following mine closure the crushers Chemical Co, Wallaroo – Mt Lyell and metallurgical plant were dismantled Fertilisers and The BHP Company, who and the mine office and workshops were also busy developing their Whyalla later became the start of the Country iron ore mines. Fire Service (CFS) State Training Headquarters, which still operates to this The Mine commenced production in June day. The quarry bench is 1.8 km long with 1955 and continued for 17 years, closing two high walls 70 m and 85 m laid back on 31 May 1972. The Mine produced at 45° and 50°. The 8 Million tonnes (Mt) 5.5 million tonnes of iron sulphide ore at of rock removed to access the pyrite was ~380,000 tonnes per annum. The ore had discarded to form the north and south an average grade of 11% sulphur that was waste rock dumps. A small south east crushed and concentrated onsite to 40% waste rock dump was remediated in the sulphur. The pyrite ore lode is a mix of two 1990’s. iron-sulphide minerals, these being pyrite (FeS2) & pyrrhotite (FeS). Concentration of the sulphide ore by crushing and grinding to a fine sand, 80% The minerals were quarried from the side passing a 75 mm sieve, produced 3.5Mt of of two steep hills using a power shovel mill tailings that was pumped to the other and trucks. The mine concentrate was side of Pyrites Road to fill a shallow farm trucked to a rail siding at Nairne and then valley to create a Tailings Storage Facility railed to Snowdens Beach, Port Adelaide (TSF). The tailings at the front edge is where it was converted to sulphuric 30 m above the valley floor and covers an acid (H SO ). Imported phosphate rock 2 4 area of 28 hectares. was treated with the acid to produce superphosphate fertiliser to sustain South Australian agriculture. 2 of 9 www.minerals.dmitre.sa.gov.au/brukunga Notes for Visitors Brukunga Mine Site Environmental concerns also continues steeply into the ground beneath the current quarry floor. The The main environmental concern at blasting and crushing activity of mining november 2012 Brukunga is caused by the natural increased the surface area of the pyrite oxidation of pyrite minerals in air and exposed to the air, significantly increasing water to form sulphuric acid, known as the amount of oxidation occurring. This is Acid and Metalliferous Drainage (AMD). an order of magnitude greater that was The small amount of pyrite still remaining occurring naturally when the minerals in the waste rock dumps and the tailings were in the ground. dam causes AMD to seep out at base of the dumps. The acid waters also dissolve In 1993-94 Australian Nuclear Scientific small amounts of other metals from the and Technology Organisation (ANSTO) minerals. were engaged to provide an estimate of how long the oxidation would continue Dawesley Creek flows north to south above previous background levels. through the Mine site and picks up Temperature and oxygen levels were contaminants, carrying them downstream monitored in a series of boreholes drilled into Mount Barker Creek, Bremer River into the tailings and rock dumps and the and into Lake Alexandrina. Soon after results were used in calculations which the mine opened and up to a construction indicate that the reactions are likely to bypass of the creek in 2003 the water continue for 240 years and up to 750 from the Mine was so contaminated years. Subsequent analysis indicates that with sulphate and heavy metals such this figure could potentially be in excess of as aluminium, iron, cadmium, and 1,000 years. manganese. The water was unsuitable for livestock and irrigation use up to 55 km In March 1999 the Brukunga Mine Site downstream of the Mine site. Remediation Board (BMSRB) was formed to replace the technical based Brukunga The geological formation hosting the pyrite Taskforce, placing emphasis on local is not specific to Brukunga and extends community involvement in developing new 40 km north and south of the Mine and management solutions to the problem. The BMSRB advise the Minister on strategies for environmental improvement and is made up of representatives from the Dawesley Creek Catchment Landcare Group, the District Council of Mount Barker, the community and DMITRE. Seepage interception During mining much of the acid water was controlled by reusing it in the metallurgical plant. After closure in 1972 Nairne Pyrites Pty Ltd employed two caretakers to collect Acid and metalliferous drainage contaminating Dawesley Creek at Brukunga Mine and pump contaminated water to a large 3 of 9 www.minerals.dmitre.sa.gov.au/brukunga Notes for Visitors Brukunga Mine Site evaporation lake on the tailings dam. In from 20 to 40kL/hr. During persistent wet February 1974 a summer storm caused periods the plant operates at a peak feed the lake to overflow and it was soon of 63kL/hr for several days or more, as november 2012 realised that the water would not naturally necessary to prevent the holding ponds evaporate. The Department of Mines overtopping. and Australian Mineral Development Laboratories (AMDEL) began to Despite all the work done from 1980 to investigate the issues. In August 1977 the 2003 to intercept and treat acid drainage State Government accepted responsibility only about half the contaminated water for management and remediation of the from the site was captured and treated, site. the remaining 50% or ~600 tonnes per annum of sulphate escaped to Dawesley In September 1980 the Government Creek. On completion of the diversion commissioned the acid neutralisation plant drain in June 2003 it became possible to to treat the acid water. The Department of intercept much more of the contaminated Engineering and Water Supply (E&WS) water, with most of the loss occurring were appointed the operators and within during high rainfall events, when there is 5 years of treatment the 10 ha lake of greatest dilution helping to produce lower acid water was removed from the tailings concentrations in the stream. dam. Contaminated water percolating through the tailings dam and from the mine waste rock dumps and benches Neutralisation treatment was then collected by 12 pumps spread plant about the mine site and treated by the plant. Acid water is collected from the The inputs to the plant are hydrated lime and carbide lime (Ca(OH) ), at pH 12, quarry bench, the waste rock dumps and 2 dilute sulphuric acid waters (H SO ) at from the section of creek bed isolated by 2 4 pH 2.3 and oxygen (O ) provided by air the diversion drain.