Motswakae’s ‘tagged neutron method’ aims to improve diamond mining

By: Tshegofatso Teseletso

The mining sector remains the cornerstone of Botswana’s economy despite the nation’s concerted efforts of diversifying from a mineral based to a knowledge-based economy. Mining is the country’s largest contributor to gross domestic product (GDP), and it is the main generator of export earnings.The precious Botswana Diamonds lead revenue generation for the country, and their handling remains a top priority if the country was to benefit maximum value of the rare minerals.

In a bid to ensure maximum cashing-in on the lucrative minerals,Botswana International University of Science and Technology, MSc student in the Department of Physics and Astronomy, specializing in nuclear physics went on a scientific invention journey to bring solutions to delicate mining and handling of the precious diamonds.

In April 2019, Motswakae Sebele ventured on research whose main objective was detecting diamonds in kimberlite using the tagged neutron method. The project was done in collaboration with the Joint Institute for Nuclear Research (JINR) in Dubna, Russia under the guidance of BIUST professor Gregory Hillhouse and JINR Professor Mikhail Sapozhnikov.The project focuses on detection of the large diamonds hidden within the ore and early rejecting or separating a barren ore from the diamond-bearing ore using 14 MeV neutrons (tagged neutrons).

Sebele explained that the current methods used in the diamond mining industry were too costly and had over the years proved a challenge to mining companies. He highlighted that diamonds exist in parts per million (ppm) in kimberlite which means mining companies are mainly dealing with barren ore (Ore without diamonds). Diamonds are also rare minerals, therefore, better methods were needed to avoid damaging the already scarce resources at discovery and mining. Inspired by this fact, he went on a solution finding mission to eliminate this economically straining challenge.

He emphasized that Botswana’s mining sector needed a subtle technique that would assist in avoiding the breakage of diamonds compared to the current excessive crushing technique. He highlighted that large diamonds were mostly affected because the ore was excessively crushed up to few millimeters, roughly less than 5 mm in some cases.“Botswana is the leading producer of high-quality diamonds. The diamonds contribute 35-40 % of the country’s revenue hence new techniques should be explored now and then to improve the mining process and continue extracting high-quality diamonds. Large diamonds generate more income for mining companies and the country,” he said.

To stress the relevance and importance of his project towards economic growth, Sebele gave examples of the famous 1,109 carats Lesedi la Rona diamond that was discovered in the Karowe mine and sold at $53 million and the 813 carats (Constellation) that fetched $63 million, a discovery by the same company.”Large diamonds are mostly beneficial, and with the use of tagged neutron method, more large diamonds can be easily discovered, protected from breakage and sell at a more desirable price that would contribute handsomely to the country’s economy,” he explained.

His determination to make a difference in the local diamond mining sector led him to international training in Russia and Dublin. Debswana Mining Company sponsored him. He said the trip helped to harness his skills and expertise exposing him to learning and working with experts in nuclear physics.During the expedition, he managed to publish an article about the new technique that can be used in the diamond mining industry and held a series of panel discussions. “I was able to visit different nuclear labs at the JINR and learn the international scope of nuclear field,”he said.

He revealed his main aim was to work with leading Russian experts to transfer the acquired technical skills of handling diamonds to the mining industry in Botswana.If everything goes according to the plan, he said the project would be introduced in the mining industry sooner rather than later. He also mentioned that even though the project was mainly focused on the diamond mining industry, it could be used in other industries like coal mining.

In his view, the technique can be used to grade coal. It produces more reliable results as compared to the vitrinite reflectance technique used in coal grading. “The technique is also environmentally friendly because it minimizes dust produced due to excessive crushing of theore and saves water. Current mining techniques use excessive water to cool the machines and to contain dust,” he lamented.

He acknowledged BIUST for providing an enabling environment that helped him to secure collaborations with other experts around the world. “I am grateful to BIUST because it is through BIUST that I managed to get sponsorship from the Debswana Mining Company and it’s through BIUST staff (my supervisor, Prof Hillhouse) that I
managed to collaborate with the Russian expects,” he appreciated.

He noted that BIUST has a memorandum of understanding with the JINR that helped him to link with Prof Mikhail Sapozhnikov’s group easily.For a word of advice to other scientists studying at the university, he said they should always remember that there is no sweet without sweat and that challenges were temporary situations that could be overcome by dedication, focus and determination.

At last, Sebele appreciated his sponsors (Debswana Mining Company) for making it possible for him to visit JINR and his supervisors for their guidance throughout the project and to everyone who believed in his dream.

Botswana International University of Science & Technology