FLSmidth has been contracted to deliver an integrated dry-stack tailings solution and a paste fill plant to Hindustan Zinc’s lead-zinc mine in Rajpura Dariba, Rajasthan.

The solution will ensure environmental sustainability and significant process water recovery, as well as reduce the footprint of the tailings storage facility, the mining OEM said.

The new order, which was booked in the December quarter, includes design, engineering, procurement, supply of equipment and the commissioning for integrated dry tailings and stacking along with tailings paste fill plant. FLSmidth will also supply two Automatic Filter Presses (AFP-IV™, pictured), two E-Disc filters and one 26 m diameter High-Density Thickener as the main pieces of equipment. The project is expected to be completed by February 2022.

This new order follows a previous tailings-related order for Hindustan Zinc at its Zawar mine site in 2018.

Hindustan Zinc operates beneficiation plants at Rajpura Dariba and Sindesar Khurd, which both discharge tailings to the same tailings pond. The tailings dam was reaching capacity for conventional wet tailings deposition and so Hindustan Zinc needed a way to resolve this issue, FLSmidth said.

The solution the company required would involve creating a small dry-stack tailings area with minimal environmental and physical footprint and also a method to backfill the mine by using an adjusted dry filter cake mix.

By choosing FLSmidth’s hybrid technology – a combination of the E-Disc filter and the AFP-IV Automatic Pressure Filter – Hindustan Zinc will now be able to achieve this and recover around 85% of process water, according to FLSmidth. This recovered process water can be reused by the process plant located at the mine site with minimum operating and capital expenses.

The cake from the E-disc filter will contain below 16% moisture and can be used for mine backfilling, while the cake from the automatic filter press, with below 12% moisture, can be stacked on the surface in a safe and compact manner, FLSmidth says.

“The solution will also significantly reduce industrial water consumption, something that is of heightened importance in water-scarce areas, such as Rajasthan,” the company said. “The site will also have zero effluent discharge, further boosting its sustainable mining goals.”

Manfred Schaffer, Mining President, FLSmidth, said the order was another strong “proof point” for the quality and flexibility of the company’s technology for filtration and engineering solutions for tailing management.

“This project resolves the customer’s challenge through optimum utilisation of available space and ensures the paste backfill requirements are met with the lowest possible operating and capital costs,” he added. “Importantly, it also secures a high level of reusable water for the mine site, which helps their sustainability efforts and supports our own MissionZero ambition.”