A series of tilting (variable slope) flume tests were undertaken at the pilot plant facility at Chuquicamata copper mine in northern Chile to study the achievable tailings beach slope for different tailings solids concentrations and flowrates. The pilot plant facility was part of a prefeasibility study into upgrading the existing conventional tailings disposal facility, to a thickened tailings disposal scheme. The tilting flume facility was included into the pilot plant trial to produce reliable data for verification of theoretical beach slope prediction models. The tests were conducted on existing tailings from the Chuquicamata plant. A pilot size (2.5 m diameter) thickener was used to thicken the slurry to higher solids concentration before feeding the tilting flume. A range of different slurry flowrates (ranging from 5.5 to 18 L/s) and solids concentrations (ranging from 56.5 to 72.5%) were tested. The testing methodology, the test results and analysis, are discussed in this paper. The actual measured beach slope (based on hydrodynamics of channel flow theory) for each flowrate and slurry solids concentration are also presented.

CODELCO is considering the implementation of high density tailings management at their Chuquicamata mine in northern Chile for its long term disposal plan. To achieve this, CODELCO commissioned the design, construction and operation of a 70 tonne/day pilot plant, fed by existing tailings. The testing programme was completed in May 2011 and consisted of laboratory rheological and characterisation assessments, pipe loop testing, beaching trials and analyses of deposition behaviour for solid contents ranging from 57-68% (w/w). This paper describes the characteristics of the pilot plant, the testing programme, the beach trial analyses and the resulting beach profile predictions based on the Stream Power theory. CODELCO also used other predictive beach slope methods, such as the Equilibrium Slope concept, which are not discussed in this paper. The final beach profile for design will be selected after an expert analysis of all methods has been completed. The fundamental objectives of the pilot plant were to determine the deposition behaviour of the tailings at concentrations of 57% (as currently produced), 63, 65 and 68% solids (w/w) and to assess thickener performance to achieve these concentrations. The key components of the pilot plant are summarised as follows and identified in Figure 1:  Pilot paste thickener (2.5 m diameter, 11 m high): Designed and operated by Outotec, with a maximum capacity of 70 tonne/day.  Pipe loops: Designed and operated by P&C. Two pipe loops of 3 and 4 inch diameter (7.6 cm and 10.2 cm) were assembled to allow operation of three configurations (78 m of 7.6 cm, 80 m of https://papers.acg.uwa.edu.au/p/1263_17_Engels/ Evaluation of the behaviour of high density tailings deposition-CODELCO pilot plant J. Engels et al.

A large-scale field deposition trial was carried out at the Chuquicamata mine's Talabre Tailings Storage Facility (TSF) in Chile to study the achievable beach slope with the current tailings in the absence of further thickening. The tailings received at the Talabre TSF are a mix of tailings from two different operating mines; Chuquicamata (CH) and Ministro Hales (MH). The field deposition trial was run with a total discharge flowrate of 100 L/s from two outlets each discharging 50 L/s. The average as-received solids content of the slurry during the field trail was 52% ranging from 56.5-40.8% (solids by weight). The trial was run for 56 days from early August to early October 2014 with continuous tailings discharge for eight hours per day. The limitation on discharge time was to prevent rapid initial build-up and possible mass slumping which would interfere with the interpretation of the results. Nevertheless the scale of the trial was such that 'continuous' discharge conditions established quickly at the beginning of each deposition day, and the trial is considered to be representative of continuous discharge conditions. As expected, discharge of tailings resulted in the formation of a plunge pool at the impact area of the slurry stream at the head of the beach then self-formed channels that developed on the beach as the slurry left the plunge pool. The tailings beach that forms by this mechanism is similar to a full-size stack. This is a clear distinction from smaller scale deposition trials that are often reported which involve the deposition at very low flow rates or of discrete batches of tailings which result in a beach formed by layers of sheet flow. The preliminary results and findings from the monitoring and observations of this trial deposition including the achieved beach slope are presented and discussed in this paper.

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