Few people connect sand and sandstone. “However, the two are very much intertwined as sand is normally made from sandstone and sandstone from sand,” said Mr Sebete Mabaleha, a fifth year chemical Technology student in the Department of Chemistry and Chemical Technology at the National University of Lesotho (NUL). Mr Mabaleha is working on a product that will see Lesotho produce its own form of artificial sand.
The product is called artificial sand because it will be man-made in a process that mimics natural sand-making. He is working with a local company called Lekokoaneng Sandstone Pty (Ltd). He hopes that his artificial sand will not only solve the problem of waste sandstone generated by the mining activities in the Lekokoaneng area, it will also open a whole new industry of pure sand making to produce sand for numerous applications.
“To understand what we are doing, think about how natural sand is made,” Mr Mabaleha continued. “Sandstone undergoes a process of weathering. This happens physically through atmospheric heat, water, and pressure.
It also happens chemically as soil chemicals dissolve binders of particles in a rock. This process can take thousands, sometimes millions, of years! However, in the lab, we are faster! Our experiments are carefully designed to apply heat, pressure and chemicals in an aquatic environment. The process removes binders which are mainly clays and organic substances, leaving purer sand. Our tests have shown that what takes thousands of years to occur, we do it in few hours!”
However, if there is so much natural sand mined easily in rivers around the country, why would we need artificial sand?
The answer boils down to sand quality. Artificial sand can be of extremely highly quality. This is because, unlike natural sand, it can be made to be free from many impurities. “We did a number of mechanical tests on the potential of our artificial sand in concrete applications, compared to natural river sand.” Mr Mabaleha said. “Due to its high quality, properties of concrete made from our artificial sand were far better than those of concrete made from natural river sand. Our results were so interesting that we are writing a journal paper on what we have found.”
However, it may still be expensive to produce artificial sand in large scale compared to mining natural river sand, so why bother? “The problem is that most people view sand as something used only in concrete. Nothing could be further from reality. Most of the products that we enjoy today are made from sand; purified sand. Think about glass, glues, decorative texture paints, abrasives, ceramics and most electronic products, all these are partly made of pure sand.
So while our sand would rival any alternatives in the local market in terms of desirability for building, we should never limit our applications to building as the alternative applications are far more lucrative in terms of returns,” Mr Mabaleha concluded.
Asked about what impact his work can make in terms of job creation, Mr Mabaleha showed that the potential of this work to create sustainable jobs is enormous. He said Lesotho has four main exposed geological formations, the potential of which has never been tapped! We have Lesotho, Clarens, Elliot, and Molteno geological formations, all of which consist of very important stones whose economic value is amazing!
“People are worried about diamonds. Rarely do they realize that the stones that we see right in front of our eyes every day, have been used elsewhere to make some of the most expensive products we enjoy today,” He said. Mr Mabaleha further showed that the stone that he uses, from the local Clarens geological formation, has many advantages as opposed to other sources of sand. “Contrary to other sources of sand, it has one of the finest sand particles that show little differences in size.”
The Clarens formation, which has been made famous by the mining of Lekokoaneng sandstone (it is mined within this formation), was developed in Lesotho, millions of years ago. The sand was brought and deposited here by wind. So wind transport demands that particles being carried be of a certain size, a very small size. Otherwise the sand would be too heavy to carry. “This is a big deal!” Said Mr Mabaleha.“ A lot of energy is expended on grinding sand particles to this fine size for many applications. However, our sand is already in the right size.”
“So my humble submission is, as a country, let us invest in research projects of this kind if we hope for economic development. Economic development has never been and will never be a product of chance!”
This blog post was originally written by NUL Research and Innovations