Modelling evaporation of paste tailings from the Bulyanhulu mine

Abstract

Accurate predictions of drying rates are desirable to optimize surface deposition of thickened or paste tailings. A series of laboratory and field trials were implemented to study evaporation from tailings at the Bulyanhulu gold mine and were compared with numerical simulations using the unsaturated flow model SoilCover. The laboratory tests included two “large-scale” experiments on 10 cm thick layers of tailings 2 m by 1 m in plan, and a smaller column test on a 20 cm thick and 20 cm diameter sample. Data monitored during these tests included albedo, volume change, degree of cracking, matric suction, water content, and drying rate. Field data included gravimetric water contents and albedo values. The model could reasonably simulate the laboratory experiments when adjustments were made to account for self-weight consolidation and the effect of volume change on the relative permeability function. The model could simulate drying in the field for up to 3 weeks after deposition before the accumulation of gypsum and magnesium sulphate salts began to affect evaporation. Cracking and salt accumulation were observed both in the laboratory and in the field. A general model for simulating drying from paste tailings should incorporate the effects of cracking and salts.

A New Procedure for Deep Sea Mining Tailings Disposal

“…For the tailings dam evaluation system, the criteria consist of economic consideration, flood and earthquake design criteria, environmental design flood criteria, water cover, long-term stability of the tailings dam, the dam safety, and risk estimation. An evaluation system for the tailings backfill consists of three parts: stability, economic consideration, and durability [32]. Additionally, there are a few reasons for utilizing the ANP method to perform an evaluation.…”

“…In the history of tailings disposal, combining different kinds of tailings disposal methods already exists. For instance, in arid and semi-arid areas, tailings are stored in tailings dams firstly; undergoing natural evaporation and consolidation by hardener, the tailings with a high concentration of water can be transferred into tailings pastes; then, the tailings paste can be backfilled into the mining site to decrease the mining footprint [32]. Table 1.…”

Cracking, salinity and evaporation in mesoscale experiments on three types of tailings

“…Previous authors have studied the effects of albedo (Malek et al, 1990;Newson and Fahey, 2003;Simms et al 2007) as upward flow advects dissolved mass and rapidly accumulates it at the soil surface, leading to a suppression of evaporation through osmotic suction's contribution to total suction. Precipitating salts may decrease the porosity and permeability or form a crust.…”

“…Previous authors have studied the effects of albedo (Malek et al, 1990;Newson and Fahey, 2003;Simms et al 2007), osmotic suction (Noborio et al, 1996;Yakirevich et al, 1997) and salt precipitation (Fujimaki et al, 2003(Fujimaki et al, , 2006. Osmotic suction is increased Environmental Geotechnics Cracking, salinity and evaporation in mesoscale experiments on three types of tailings Simms, Soleimani, Mizani et al as upward flow advects dissolved mass and rapidly accumulates it at the soil surface, leading to a suppression of evaporation through osmotic suction's contribution to total suction.…”

“…Certain tailings management methods in the Canadian oil sands industry, such as Suncor's tailings reduction operations (Caldwell et al, 2014) and Shell's atmospheric fine drying technologies , use evaporation to reduce tailings volumes. Evaporation from tailings has been investigated in the scientific literature Simms et al, 2007) and in numerous specialty conference proceedings for several tailings types Innocent-Bernard et al, 2014;Rozina et al, 2015;Simms et al, 2010). Beyond tailings, evaporation is important to a large class of geotechnical and geoenvironmental problems (Vardon, 2015).…”