The large demand of mineral resources and large-scale mining operations produces a great deal of waste. One of the most important environmental considerations at any mine is how to manage these large volumes of waste so as to minimize the long-term impacts and maximize any long-term benefits. One category of mine wastes that can be produced is tailings: a residual slurry of fine particles and water in variable concentration. The process that reduces the impact of these large volumes of tailings is the filtration.

Dewaters the slurry changing its physical characteristics and making it a solid-behave material while recovering liquid phase that can be send back to the process. Filter-press is one of the most popular equipment for these purposes. Tailings dewatering decreases pore water and spaces and reduces the volume and potential toxicity of seepage and residual waste material results less reactive.

Features of filtration plant and tailings must account for the mineralogy of waste material. Some studies showed how types and contents of clay minerals had an impact on the filtration process changing the behavior of material. Ma et al. found that clay minerals affected the dewatering of coal slurry. Filtration tests showed that the presence of small amount of kaolinite and montmorillonite caused a significant reduction in the filtration velocity and porosity, and a great increase in the average specific resistance [1]. Grosso et al. investigated the effect of small contents of smectite on filterability of a slurry [2]. All samples studied where smectite mineral is present, even in small concentrations (less than 1%), were characterized by low filterability.

We develop, for the first time, quantitative relationships between the mineral phase contents and the filterability parameters. We prepared several standards according to the classification of fine-grained clastic sedimentary rock units. These samples are representative of tailings that can be collected from different sources. The main minerals that we mixed in different concentrations were quartz, carbonates and clay minerals, swelling and non-swelling, such as smectite and kaolinite. Some samples are composed by one type of clay mineral, others are composed by both types of clay minerals to point out the impact of each clay mineral on filtration.

The filtration tests were performed in a Nutsche Filter as well as in a small-scale filter press. Both devices belong to Diemme Filtration, one of the leading specialists in the field of solid-liquid separation for industrial processes. We obtained values for each standard of specific resistance of cake and time of filtration. These parameters were correlated with qualitative and quantitative mineralogical characteristics of different samples.

We highlighted the effects of each type of phase, in particular of clay minerals, in certain concentrations on filtration properties. We found that the average specific resistance of cake increased with the content of smectite.

High resistance means high time of filtration, low velocity of filtration, and consequently increased Capital Expenditure (CapEx), i.e., filter press and its ancillaries sizes, and Operating Expenses (OpEx), i.e., energy demand for equipment operation. Predicting the...