Encountering young, enthusiastic and fresh individuals’ perspectives on technological developments in the mining industry is a rare occasion, especially for women and especially within the coal sector which is still considered a ‘dirty’ commodity. Nonetheless, highly intellectual young women are proving they can and are willing to contribute towards advancement within coal’s minerals processing sector and are undeniably an inspiration to up and coming mining-focused generations, writes LAURA CORNISH.

Attending the Southern African Coal Processing Society (SACPS) biennial conference in Secunda in August, Mining Review Africa found this to be true. Two of the North-West University’s female chemical engineering students, Elmarie Peters and Nikki Hughes, attended the conference and delivered presentations on dry coal beneficiation and fine coal dewatering. These were based on the research and findings of their Masters degrees.

Fine coal recovery

Peters, who was awarded the 2017 SACPS ‘Student of the Year’ award following the submission of her M.Eng. dissertation “Adsorbent assisted drying of fine coal” at the end of 2016, presented on the topic – the result of two years of work.

The post-graduate committee of the North-West University selected to award her the degree, cum laude, with a final mark of 86%. Both examiners, external to the university, concluded that her dissertation was well written and showed that the research was done extensively and thoroughly and is of great relevance to the industry.

In a one-on-one interview at the conference, Peters notes that her inspiration for her Master’s degree was based on the challenges around the recovery of fine coal in South Africa. “An increase in mechanisation activities has resulted in an increase in the volumes of fine coal generated which is susceptible to moisture retention and difficult to dewater,” she explains. The industry traditionally makes use of heat that provides desired moisture levels at high cost, or mechanical practices that process the coal but are not very effective in attaining desired moisture levels . “If this material is not discarded, it is reintroduced into coarse coal circuits which unfortunately affects product quality.”

Under the guidance of the university’s Associate Professor Dr Marco le Roux, Peters examined a new and innovative technique to dry fine coal through the addition of a drying media. And while it proved effective using a stationary drying technique, the addition of a gradual cascading motion increased the drying rates further, with moisture levels in the coal fines dropping from about 30% to below 8%. “This was our target and would be economically attractive for the industry,” Peters, who has a SACPS bursary, explains.

Deriving a sampling method to obtain a representative of the drying curve proved difficult but was overcome, as was the challenge of gathering vast amounts of information and finding explanations for every part of the project, which in some instances required additional test work and research.

The technique, which differs in terms of regeneration, by comparison with other Chinese techniques, is what makes the project unique and will enable it to be converted into commercial opportunities down the line. This after advancing the project in conjunction with coal research specialist Coal-Tech – focusing specifically on flotation tailings across the variety of South African coals, Le Roux notes.

In 2017 Peters enrolled for a PhD in dry fine coal beneficiation where she will study the applicability of air dense medium fluidised beds for use with -13 mm South African coals. “It will hopefully take me another two years to complete.”

Peters was born in Namibia but acquired South African citizenship this year and is excited to immerse herself in the industry.

“It was never my plan to work in the coal industry but I have really enjoyed it and plan to stay in the sector.”

Fine coal dry beneficiation

Hughes delivered her presentation at the conference on dry beneficiation of coarse coal using air dense medium fluidisation (DMF) which is the topic of her Master’s degree – due for completion at the end of this year.

To evaluate the effects of subjecting the coal to air on coal fractions between +5 mm and -13 mm and moisture contents below 5%, Hughes had to design a new, larger DMF bed to conduct her experiments on. “Nikki’s bed design was exceptional,” Le Roux highlights.

“My biggest challenge was optimising and commissioning the bed and thereafter realising that the quality of the coal has a major effect on the performance of the bed,” Hughes says.

The remainder of the year will see her complete her test work in order to analyse the effects of the bed and show how different coal qualities perform differently. The results will ultimately form part of Coal-Tech’s focus on dry coal beneficiation which could offer significant potential for coal processing in arid regions.

Looking forward, Hughes is keen to enter the industry and contribute to technological improvements in the minerals processing sector – for any commodity. “I am driven by the desire to take something simple and transform it into something valuable that most people take for granted. I believe engineers play a major role in driving the economy of a country and I am eager to contribute towards this.”