40% Magnetite Savings Achieved By Power Nozzle

Mines around the world are faced with many challenges on a daily basis, but the one which is really impacting mining operations, is the scarcity of resources. Mines are continuously looking at improving their production yield, and concepts such as zero-water-usage and material-usage-efficiency have all become part of their everyday vocabulary.

Mines in general are especially focused on recycling their water, aiming for the point where production doesn’t require any potable water – and only recycled (rain, sewerage, run-off and excess underground) water is used. According to Craig Sheridan, Associate Professor at the School of Chemical and Metallurgical Engineering at the University of the Witwatersrand, “Waterless mining is where water is consistently recycled and reused in a closed circuit – (this) is the end goal of being water efficient,”. (Closing the Loop by Toni Miur; Mining Decisions issue #2 – February 2018.) Recycled water usage, however means that the water is likely to contain sometimes large particles of solids.

Looking at coal mining specifically, a particularly important step in the coal preparation process, is the process of coal washing. Many of the run-of-mine coal today requires this selective process where all impurities, such as soil and rock, are removed to improve the quality of the coal product sent to industry. As part of this coal washing process, one of the methods used to treat coal, is magnetite. Magnetite, together with water, is used in the coal mining process to create an environment conductive to the separation of the coal and the impurities it carries. This process of using magnetite as a separation medium can be quite a costly exercise, and it is therefore important to reuse the magnetite as much as possible. This brings us to one of the biggest challenges which coal mines in particular are facing when trying to reuse magnetite: the consumption of the magnetite during the washing phase. High magnetite consumption during the coal washing process generally cost companies and mines millions of Rands each year, compelling coal mines to actively explore magnetite-saving measures.

One such coal washing company, operating some of the highest number of coal washing plants of any independent contracting company in South Africa, was faced with a very similar challenge. They were experiencing magnetite consumption of around 0,7kg per ton on average (which was within their tolerable range), but these results continued to move closer to their acceptable magnetite consumption limit. Since coal washing is one of their core services, it remains a key focus for them to continually explore ways to be as efficient as possible with all the resources and materials used during the coal washing process.

It was during one of these exercises that they have been introduced to a new, innovative solution on the market, called the Afri-Tech Power Nozzle. The Afri-Tech Power Nozzle, developed and distributed by Afri-Tech in South Africa, is a patent-pending, self-cleaning spray nozzle designed with two goals in mind: to use process water without the nozzle getting blocked, and to be one of the most efficient washing nozzles on the market with its double-washing spray action.

Traditional spade nozzles block easily and in almost all cases a shutdown of the immediate process area is needed to clean these. This means that the use of recycled water on the plant will result in many hours of downtime and reduced productivity. The Afri-Tech Power Nozzle however, is completely self-flushing, ensuring a constant spray of wash water on the product. And because the Afri-Tech Power Nozzle can be remotely cleaned, use of this innovative equipment eliminates the hours of downtime for cleaning, thereby optimising productivity and benefiting the bottom line of any mine or plant.

The results speak for themselves. The coal washing company immediately started seeing magnetite savings of around 40% at the plant where they have installed the new Afri-Tech Power Nozzle, and they have since continued with rolling this washing nozzle out to their other plants. The graph below shows the actual results before the Afri-Tech Power Nozzle was installed, and the decline in magnetite consumption after installation.