In the processing of agates, geode sawing generates a residue comprising diesel oil, moisture, and fine agate fragments. This process is usually carried out by small companies and the waste material generally accumulates in courtyards, waiting for a suitable destination to be determined. In this context, the aim of this work was to study the removal of the liquid fraction (oil and some water) from this agate sawdust residue (ASR) by mechanical compression. The experimental work included waste material characterisation and fluid removal assays. The oily residue was processed by compressing it at a laboratory scale, where the main variables were pressure (2.0 MPa, 4.2 MPa, and 6.4 MPa) and temperature (5？C, 23？C and 60？C). The experiments were performed in triplicate and the differences between means were statistically analysed. Thereafter, the treatment of oily residue was also carried out in an industrial hydraulic press (11.7 MPa at 23？C). The ASR sampled for this work was a solid-in-water-in-oil sludge, comprising (by w/w) 19.0% diesel oil, 8.5% water and 72.5% silica (SiO2). The laboratory and industrial trials showed that the removal of liquids is a function of the applied pressure-the higher the pressure, the higher the fluid removal-and the best temperature, which occurred at 23？C. Pressures above 6.2 MPa changed the ASR composition to approximately 3.6% oil and 3.5% water, corresponding to approximately 80% of liquid removal, by weight. The process allowed a reduction in volume, increased oil recovery, and an improvement in the material’s handling properties. Regarding the solid fraction, it was now in a better condition to be used in red ceramics or co-processing in cement production kilns.
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