Rainstorm, a Perth-based dust control company, has a simple mission – keeping dust emissions down without wasting water.
One of the oldest methods of suppressing dust is by applying water. Adding water to a fine material, while in the ground or as they are agitated, increases the weight of each dust particle, making it much less likely they will become airborne.
However, using large amounts of water to suppress dust can be detrimental environmentally and economically, especially in periods of drought and water restrictions.
Mason Trouchet, Group Technical Sales and Marketing Manager at Rainstorm Dust Control argues that every drop of water spent on dust control is a drop of water lost.
“I am a firm believer in effective dust control treatments to conserve water and improve health and safety measures, especially for large-scale mining applications,” he says.
Trouchet is part of the product development team for Rainstorm and is involved in establishing dust control services and procurement technology transfer in international markets.
One such system is the Point of Dust Extinction or PDX. PDX is the result of more than 25 years of research into non-standard ore and soil stabilising agents, developed by combining surfactant wetting agent formulations with novel, biological-based (rather than chemical), active ingredients. This highly-concentrated liquid biochemical is biodegradeable and non-toxic.
It aids wettability and friability, helping lower ultra-fine ore dust extinction moisture (DEM) and improving material handling of ore movements. When added into the mining ore stream, PDX significantly reduces dust, lowers the water levels required for DEM and minimises the environmental impact in comparison with petroleum-based water extenders.
The system is made up of three components: Dispersants, trace elements and organic compounds. Dispersants in PDX help reduce the surface tension of water and promotes the uniform transmission of moisture throughout the ore. Water adhered to the fine particles is released, which can result in a significant reduction in the volume of water required for DEM.
Trace elements in PDX assist ionic exchange reactions between fine particles in the ore. Ionic bonds are formed as a result of the attraction between oppositely-charged ions and ionic exchange is the capacity of ions to exchange with other ions which have a smaller charge net. In addition, much of the adsorbed water at the interface of the clay particles is altered to improve moisture-to-surface-area wetting ability for the long term.
Organic compounds in PDX serve primarily to modify excess ion exchange points in the ore lattice and alter the behaviour of adsorbed water.
PDX is more effective when added to an ore body early in the materials handling process, with immediate chemical changes to fine particles becoming apparent. Mechanical mixing through the material handling process creates a uniform moisture content within the ore, minimising the amount of additional water required in the process stream.
PDX is only effective on the fines components of the ore, with application rates capable of being finetuned to suit fines and lump ratios. An application rate of one litre of PDX for 10 to 25 tonnes of ore fines is recommended, depending on the site conditions.
The company has operation bases the Pilbara and Perth Western Australia, to provide bulk supply of the product to local mines.
Trouchet says data has driven the development of new innovations in dust control, along with strategic partnerships.
An example of this can be seen in Rainstorm’s partnership with Shockwave Gel Technologies which has developed a way of tackling the difficult problem of dust being generated by blasting.
The solution was to replace raggregate stem with a specialised Stemgel LR2, which provides major containment that impacts on blasting efficiency. Pressure waves contained in the rock help bring about greater fragmentation and a number of downstream benefits.
“The subsequent benefit of that powerful containment is a sizeable reduction in noise and dust,” Trouchet says.
“As the gel is expressed from the blast and becomes airborne, dust particles flocculate in mid-air and fall to the ground.
“In the past, drill and blast technologies have focused on explosives, detonation timing hole stability and moisture. Very little attention has been given to containment. It’s that unique characteristic of Stem Gel to measurably reduce noise and dust output from blasting that makes it such a massive game-changer.”