Working with Vedanta Zinc International’s Black Mountain mine in the Northern Cape to enhance safety in its milling plant, Multotec Manufacturing recently designed, manufactured and installed an automated rod charger for the mine’s rod mill.

Holder of the Southern African Institute of Mining and Metallurgy’s prestigious Health and Wellness Award, Black Mountain Mining had been looking for a solution that would reduce the risks associated with the manual handling of mill rods. Each rod measures almost five metres in length and weighs up to 240 kg. Rod mills are used extensively as primary mills in many mines, with the rods acting as grinding media. As the rods wear down, new ones have to be introduced regularly to ensure grinding efficiency is maintained.

According to Jannie Genis, technical sales representative at Multotec Manufacturing in Cape Town, the concept for the rod charger was developed in close consultation with the plant engineering and production personnel at Black Mountain, and leveraged the substantial mechanical engineering expertise within Multotec.

“The Multotec Cape Town branch, under the leadership of Vivian Rocher, put together a team that took the concept into the design stages, customising the unit to exactly suit the site plan at Black Mountain,” Genis says. “After input and suggestions from the customer, we were able to advance the project to manufacturing stage in Cape Town, where complete construction took place.”

The charger went into operation at the mine in mid-2016 and has effectively eliminated all manual handling of mill rods, successfully achieving the project goals.

“There is now no need for any person to be in the mill to guide the rods into place,” Genis says. “Only two people are involved: one to operate the unit, and one to check that the rods feed smoothly into the mill.”

Another significant advantage is the reduced time taken to conduct the rod charging; the complete process has been cut down from over an hour to just about 25 minutes. This means more production time and has also allowed the more frequent charging of rods, from twice a week using manual methods to three times a week now leading to better grinding efficiency.

“The customer expressed its satisfaction with this solution, as it addresses both safety and ease of use, while enhancing the productivity and efficiency of the mill operation,” Genis says.