VNIIНT, Moscow, Russia:

V. A. Tolkachev, Lead Researcher
D. V. Maynikov, Senior Researcher, e-mail: didima06@mail.ru
N. P. Paskhin, Senior Researcher

When compared with conventional technology, in-situ leaching (ISL) offers the most advanced technique for processing certain ores. Even though ISL delivers clear advantages, the implementation of such processes is associated with certain difficulties. One of them is related to a great number of solid particles contained in the leach solutions that are delivered in the injection wells. Such solid particles accumulate in the wells leading to clogging and lower throughput. To prevent such negative developments, the solutions need to be clarified. This paper describes a high-efficiency clarification technique for low-concentration suspensions, which offers simple practical solutions and a minimal equipment cost. A clarification unit with the capacity of 120 dm³/h was used to carry out a generic study of the process using standard test solutions. The unit comprised a flocculator, a plate settler, and a filter with fibre filler. With the concentration of solids in the initial suspension being between 60 and 850 mg/dm³ and the consumption rate of a 0.1% solution of the nonionic flocculant Praestol 2500 being 1–2 g/m³, clarified solutions were obtained with the concentration of particulates being 1–2 mg/dm³. The authors of the study used a test unit to demonstrate the key clarification process parameters, which can serve as the basis for sizing the industrial units. The paper describes the results of a study that looked at the injection solution clarification processes adopted at Khiagda site, where the process of clarification follows a sorption process. A filter with the diameter of 100 mm and the height of 2 m with fibre filler, as well as a filter with granular filler (AMP resin) with the diameter of 50 mm and the height of 1 m were used for clarification. This helped bring down the average concentration of particulates in the solution from 4.56 to 0.92 mg/dm³ for the filter with fibre filler and from 8.7 to 1.5 mg/dm³ for the filter with granular filler. The investigated clarification technique is proposed for companies relying on in-situ leaching, as well as for solution clarification processes in related industries.

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