Author: AJ Strauss
Conference: SANCOLD Annual Conference
Date: September 1-3, 2015

ABSTRACT
On 27th February 2014 solids were noted to be discharging into the Return Water Dam below the Selati Tailings Dam at Foskor in Phalaborwa, indicating a decant failure. All parties involved reacted quickly to curb the discharge of solids and minimize the risk of catastrophic failure of the facility. Within days, a temporary filter was constructed on the outlet, followed by the design and construction of a medium term filter, while a solution is being sought for the permanent sealing of the decant outlet.

COMPANY BACKGROUND
Foskor (Pty) Ltd is a company whose primary focus is the production and marketing of Phosphoric acid and related products, consisting of two divisions situated in Phalaborwa and Richards Bay respectively. Phosphate rock is supplied by Foskor Phalaborwa to Foskor Richards Bay, where Phosphoric Acid and granulated fertilizer is manufactured.

The Phalaborwa division consists of Mining, Communition & Beneficiation, and Tailings management, and the Richards Bay division is divided into Phosphoric Acid, Sulphuric Acid and Granulation production. The Phalaborwa Operation produces approximately 2.1 million tons of phosphate annually. As part of the mining process, approximately 45,000 tons of mine residue need to be disposed daily on mine residue facilities.

The Phalaborwa operations are currently using the Selati and Southern Tailings dams for this purpose. The Selati Tailings Dam (Selati TD) covers approximately 1,110 hectares and the Southern dam (Southern TD) covers about 244 hectares.

Tailings are mainly deposited on the Selati tailings dam with the Southern dam serving as a bypass capacity in case problems are experienced at the Selati Transfer pump station. Tailings are deposited via 1 m diameter cyclones which are fed from the Tailings Transfer Pump Station by way of 5 feed lines installed to distribute tailings material around the facility.

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