The Bullamine project is an investigation into the opportunities for developing iron mining (magnetite) operations in the south west part of Western Australia, east from Perth. The project covers over 3,000 km2 under 15 tenements.
Figure 1. Bullamine Project location.
Iron mineralisation identified by Western Mining Corporation in the 1970s was the initial attraction and led to the acquisition of a tenement (E70/2846) adjacent to the town of Northam located 70 kilometres east from Perth. The area of interest rapidly grew following a joint venture with Ferrum Crescent Resources (then Washington Resources; for E70/2719 & 2720) and subsequent application for an additional tenement (E70/3462) abutting to the north. This initial area is shown as the Nor 1 tenement block in Figure 2.
Figure 2. Bullamine project tenements (3,496 km2 at 30 June 2010) in the Northam-Merredin area in south west of WA are shown in blue outline. Tenements are shown draped over regional magnetic data (in places at 1.6 km line spacing). Other projects exploring for magnetite in the area include Yerecoin (Giralia Resources NL (ASX:GIR)) and Jubuk (Magnetic Resources NL (ASX:MAU)).
Detailed airborne magnetic survey data (200 metre line spacing) over parts of the Nor 1 tenements were acquired during 2007. Processing and interpretation of these data identified a number of targets indicative of rocks prospective for iron minerals. The individual target units range in length from 200 metres to 5,000 metres.
An extensive network of rail lines servicing the region's wheat growers and both rail and road links to Fremantle Ports' Kwinana facilities - one of Australia's major bulk cargo ports, makes relatively small scale production of iron concentrates for sale and export potentially feasible.
Critical parameters, in addition to the presence of and access to sufficient ore, are mining, processing and rehabilitation costs.
The Company is exploring for magnetite deposits of all sizes and believes that magnetite in banded iron formations as narrow as 20 metres wide may prove economically viable to mine. Key to this possibility is how efficiently iron concentrates can be produced from the weathered magnetite mineralisation generally found to a depth of 30 metres below surface and overlying fresh mineralisation. Mining the upper parts of deposits from numerous relatively small scale open cut pits may prove economically viable.
Large deposits of magnetite may also exist within RLC's tenements. Substantial magnetic anomalies, which may be related to magnetite mineralisation, are present within several of RLC's Bullamine tenements. For example, Giralia Resources NL announced to ASX on 7 July 2010 an "Inferred Mineral Resource" estimate of 186.8 Mt @ 30.9% Fe for its Yerecoin Magnetite Project located about 30 kilometres north-west from RLC's Nor 1 tenements.
One of the principal costs involved in producing an iron concentrate is determined by the particle size to which the ore must be crushed and ground in order to liberate the iron particles. Many magnetite ores require grinding to 75 micron or lower before a concentrate of suitable grade for sale can be achieved. The degree to which an ore must be crushed or ground impacts costs in several ways. Firstly, grinding is expensive. Secondly, the coarser the concentrate product the easier and cheaper it is to transport. Thirdly, larger waste particles will require less agglomeration if used as back-fill as part of the rehabilitation of each pit.
Drilling in late 2008 at Cleansweep, the first target for which land owner consent to exploration and mining was gained, identified bands of magnetite which testing in 2009 revealed had exceptional processing characteristics (excellent liberation at 500 micron crush) and very low levels of impurities. 500 micron is half a millimetre, a fine sand not a powder.
sample of core recovered from the Cleansweep target. Results demonstrate that relatively coarse grind sizes
(80% passing 500 micron) are sufficient to liberate magnetite.
(Assay by XRF, ALS Chemex, 2009, Samples from interval 42 - 50 m bore hole 6)
The limited drilling conducted at the Cleansweep target to date has indicated that the mineralisation here is restricted to a steeply dipping composite main band of about 20 metres thick extending for less than 500 metres strike length. Whilst the dimensions and location of Cleansweep immediately adjacent to a bitumen road make Cleansweep unlikely to be economic to mine, the presence of such high quality and readily processable magnetite is highly encouraging.
During 2009 other companies were also reporting occurrences of high quality magnetite mineralisation in the region. This suggested that the characteristics of the mineralisation identified at Cleansweep was not an isolated occurrence and the Company applied for tenements covering the majority of the larger magnetic anomalies evident in regional magnetic data within 150 kilometres of its Northam tenements. At 30 June 2010 the Bullamine project comprised a total area granted and under application of 3,496 km2 covering : Nor 1, Kell 1 to Kell 7 (granted) and Ben 1 & 2 (under application) (refer to Figure 2).
Scout drilling in July 2010 at Nor 1 (E70/3462) intersected magnetite mineralisation at two magnetic anomalies, Bollo 1 and Bollo 2. The Bollo 1 & 2 magnetic anomalies measure in excess of 500 metres and 800 metres strike length respectively. Early results from the drilling suggested the mineralisation occurs from surface within a steeply dipping body of about 20 metres thickness at each target.
