Heavy mineral sands

Broken Hill Prospecting has taken advantage of a recent opportunity to acquire a large portfolio of heavy mineral sands (HMS) prospects south of Broken Hill. The project includes known heavy mineral sand deposits within five Exploration Licence (Group 10) Applications. The areas include titanium and zirconium mineral sand deposits in the northern Murray basin of NSW.

The five areas contain 20 known HMS prospects, all of which have been investigated by other mineral explorers including Iluka Resources Ltd, Bemax Resources Ltd (now Cristal Mining) and Westralian Sands Ltd. Several of the prospects have been shown to be of considerable size. Recent advances in technology have resulted in lower cost and competitive processing options for fine-grained heavy mineral sands, unlocking an opportunity to take a fresh look these HMS prospects.

Broken Hill Minerals Pty Ltd, a wholly owned subsidiary of BPL, lodged applications for the five tenements which have a combined area of 858 square kilometres (see location map below).

Figure 1: Nanya location map

HMS miner Cristal Mining operates two mineral sands mines (Ginkgo and Snapper) in the NSW Murray Basin and a mineral separation plant at Broken Hill. According to Cristal’s December 2013 quarter report, these mines produced 163,479 tonnes of ilmenite and yielded sales revenues of $A309 million during 2013. In mid June 2014 the NSW Department of Planning and Environment gave a green light for Cristal Mining’s third mineral sands mine between Balranald and Ivanhoe.

BPL intends to evaluate the new HMS prospects using a variety of recent exploration and development advances, many of which were not available during previous assessments of the areas. The application of sonic drilling techniques to mineral exploration provides effective and total sample recovery in unconsolidated sandy overburden. It does that by retrieving a continuous, undisturbed core sample to reduce waste by up to 80% relative to conventional drilling methods. Sonic drilling can be 2-3 times faster than percussion air core drilling. BPL will consider sonic drilling to evaluate the HMS targets which the company selects to drill test.

Many of the prospects BPL has selected contain a large proportion of fine-grained heavy mineral sands and silts. Traditional separation and recovery processes for heavy minerals in fine-grained sands are difficult and costly.  BPL will investigate new developments in spiral separators, which have recently focused on the processing of fine mineral particles. New spiral separators can effectively treat HMS material <0.1 mm diameter.

Other, recent mineral separation applications for fine grain size sands include the Allflux process which is based on the fluidised bed principle and uses a two-step process to eliminate pre-thickening. Fine particles form an autogenous fluidised bed on which lightweight material floats and can be removed.

Some of the ilmenite separated from HMS mining could be amenable for upgrading to titanium pigment through the use of sulphuric acid. This may also aid BPL’s plans to establish a sulphuric acid industry associated with cobalt recovery from the company’s Thackaringa cobalt deposits.

During 2010-2012, mineral sand product prices rose from values typically less than US$600/t to more than US$1,500. Prices have since settled to about US$1,000/t for most mineral sand products. In a mineral sands market update in late March 2014, Iluka, one of the world’s leading producers of titanium and zirconia, reported that more favourable demand dynamics are emerging in the pigment sector (the major end use sector for titanium dioxide) which, if sustained, should lead to improved sales opportunities for both rutile and synthetic rutile. The report noted improving confidence levels and that at the time of Iluka’s March 2014 quarterly production announcement Iluka considered that ilmenite and rutile prices may have found a floor.

Minerals chart

Figure 2: Minerals sand prices

According to Iluka the medium term fundamentals for zircon and high-grade titanium dioxide products are favourable and growing demand for mineral sands products will be driven by increasing urbanisation, consumption growth in developing economies and new applications.