A bulk sample of beneficiated fly ash was sent to China late last year to produce magnesium and cementitious material as part of the product’s first full scale commercial smelter tests.

The company says its patented hydromet extraction process, which it has been working on for more than a decade, results in a cementitious material that appears to behave like a conventional pozzolan (volcanic ash) after two weeks.

The trial involved a load of 40MPa nominal grade shotcrete obtained from Western Suburbs Concrete in New South Wales in such a way that one third of the cement was left out, and was then split into three by discharging 0.40 cubic metres into each of three mini-agitators.

One third of the outstanding Gladstone general purpose cement was added to the first mini-agitator, another third of cementitious content Bayswater fly ash was added to the second, and 30% of Latrobe’s cementitious material was added to the third mini-agitator.

Each was mixed for five minutes and used to produce test specimens for performance assessment to limit the effect on performance of variations in the mix design as batched so that the influence of the cementitious additives could be discerned more clearly.

Compressive strength development is normally assessed at 28 days, but the samples were tested after seven and 14 days respectively.

So far the unconfined compressive strength is on par with GP cement.

Previous test work showed that the Latrobe cementitious material mix and the pure GP cement mix reacted in the same manner in the initial seven day period, however in the most recent batch of tests there was a significant lag at the one week mark.

While work is ongoing to assess why the material behaved differently, by the midway point both the Latrobe cementitious material mix and the pure GP cement mix surpassed the conventional fly ash mix in strength development suggesting that the fine grind and pozzolannic characteristics of the company’s cementitious material will produce an excellent compressive strength after 28 days and later.

Latrobe will next sample its cement mid-March, and again at 56 days in late April.

Following the completion of the cement tests, Latrobe will be able to start finalising its negotiations with potential customers who have expressed interest in entering into long-term supply agreements for both its magnesium and cementitious material.

The company has also begun negotiations with its major suppliers and over the next six months these commitments will be formalised in writing.

The major commodity cost elements are ferrosilicon, natural gas, fly ash, dolomite, lime and soda ash.

The company also continues to work towards its long-held dream of developing a 5000 tonne per annum magnesium plant at the end of 2016, which would be sufficient to meet 50% of Australia’s annual domestic consumption, all of which is presently imported.