Analysis of the useable properties of coal-water fuel modified with chemical compounds

• Coal-water-additive slurries with low viscosity and density were obtained.
• Suspensions formed of coal have the most favourable usable parameters.
• Suspensions with sodium methacrylate are most stable.
• A method for the preparation of stable coal-water suspensions was developed.
• Used additives allowed to modify their useable properties.

Due to the protection of the environment, one should seek to rationally use conventional fuels and explore new ways to obtain more energy per unit of fossil fuel. For this reason, attempts have been made to prepare coal-water slurries. Coal materials that belong to different assortments: a qualified steam coal (q. s. coal), fine coal and sludge coal were used. The tests were performed on a laboratory scale in a ball mill. The suspensions contained coal material, water and a stabilising agent: sodium methacrylate, Triton X-405 or rapeseed oil. On the basis of the results, the most favourable parameters of process have been chosen (type of raw material and additive, additive content and grinding time). The most favourable process parameters of preparing coal-water suspensions were as follow: q. s. coal with sodium methacrylate as an additive in an amount of 8.0 g/kg and 60 min milling time. These parameters enabled to obtain suspension characterised by stability at 9.4 mm, the equivalent diameter of particles had 6.3 μm, density was equal to 1.16 g/cm3 and viscosities values were 22.2 mPa·s (shear speed of 100 rev/min) and 12.7 mPa·s (shear speed of 200 rev/min). The resulting suspensions are characterised by low viscosity and density, small equivalent diameters and high stability.