OM Holdings
It’s been 18 months since OM Holdings’ Bootu Creek manganese mine reopened. Now, an $8.2 million Tailings Retreatment Plan is under development which is expected to produce an additional 250,000 tonnes of manganese over the next eight years.
“Given the significant stockpiles of lower grade ore and heavy media reject material, the Tailings Retreatment Plant is expected to produce approximately 250,000 tonnes of manganese fines per annum for approximately eight years.”
IN 2015, OM Holdings subsidiary OM Manganese’s Bootu mine was placed into the hands of administrators as global market conditions for manganese deteriorated.
It was a tough time for the mine and surrounding Tennant Creek community; 140 jobs were lost when the mine was put into care and maintenance.
But once mining activities resumed in February 2017, positive sentiment and jobs returned to the region.
OM Holdings became one of the ASX’s top performers for the year, rising from 15 cents a share in January 2017 to over a dollar per share by January 2018.
OM has its fingers in more than mining; with operations in smelting, trading, and marketing and trading of ores and ferroalloys, the company continues to focus on growth and generating value from its assets, including its Bootu Creek operation.
Bootu Creek
Manganese ore production for the June quarter of 2018 at Bootu Creek totalled 185,600 tonnes at an average grade of 35.67 per cent manganese, of which 149,762t was exported.
Mining activities during the quarter continued in the Shekuma 6B and the Chugga Far North A pits.
“Mining in the northern side of the Shekuma pit was hampered by numerous fault structures, ground water ingress and a footwall slip while Chugga Far North started to present continuous ore drill floors,” the company said in a statement.
“Concentration of the mining fleets within the eastern limb of the Bootu Creek Syncline is expected to maintain mining efficiency and reduce unit costs further within the mining operations, given the deposits relative proximity to the processing plant, mining workshop and associated infrastructure.
“Mining of the Gogo 5B deposit was completed in May and higher grade ores from the Chugga Far North and Shekuma deposits will form the basis of plant feed for the next two years with improved processing plant mass yields expected.”
The mine’s new tailings retreatment plant project, set for completion later this year, also aims to generate sinter feed for its Sarawak smelter in Malaysia.
Tailings Retreatment Plant
Metallurgical test works conducted earlier this year indicated the potential to utilise existing tailings stockpiles and HMS plant reject material to reprocess a saleable 36 per cent to 38 per cent manganese product.
The process involves feeding the tailings directly into a circuit, while the reject material is crushed through a two-stage closed circuit crushing plant.
“The existing Secondary Processing Plant crushing circuit is planned to be modified by adding an additional crushing/ grinding stage and wet screening facility so as to further crush/grind the HMS reject material,” the company stated earlier this year.
Based on the mine’s March processing plant results, about 10.8 million tonnes of tailings with an average grade of 10 per cent manganese and about 3.4mt of HMS reject material are stockpiled on site.
Both tonnages are set to increase by 1.6mt respectively, and the total inventory estimate of 17.2mt was also expected to be processed.
OM Holdings said engineering design of the plant was nearing completion, but had been extended in order “to better comply with Australian standards”.
“Delivery is still anticipated within 2018, and the plant is expected to be commissioned in the March 2019 quarter,” the company stated.
“The capital cost of approximately $8.2 million is expected to be funded from internal operating cash flows.
“Given the significant stockpiles of lower grade ore and heavy media reject material, the Tailings Retreatment Plant is expected to produce approximately 250,000 tonnes of manganese fines per annum for approximately eight years.”
Exploration
The Bootu Creek project area contained a number of manganese deposits, including the abandoned Muckaty mine, worked from shallow open pits between 1955 and 1963.
While no exploration drilling was completed in 2015 or 2016, in 2017 drilling resumed; albeit limited to a small reverse circulation drill program consisting of 11 drill holes for 1230 metres.
An exploration program tested the potential of both the Gogo and Shekuma deposits, while a limited exploration program of six drill holes tested a shallow target located to the northwest of Masai deposit.
Both programs were located on ML24301 and returned encouraging results, but no significant increase in defined resources.
OM Holdings said exploration drilling of several untested geophysical anomalies (GAIP) for Renner Springs and follow up of a prospect located to the northwest of Masai was planned for 2018.