What Does Hydraulic Blast Furnace Slag Mean?
Hydraulic blast furnace slag is the hydraulic refuse resulting from the reduction of ore in a blast furnace. This slag has a low impact on the rheological and fluid loss properties of a drilling fluid. It is used for the setting of drilling fluids that are difficult to convert to cement with other techniques of solidification. Hydraulic blast furnace slag is easily available from multiple sources in large quantities and is more consistent in quality than Portland cement.
Trenchlesspedia Explains Hydraulic Blast Furnace Slag
Hydraulic blast furnace slag is created by quickly quenching a molten stream of slag exiting the furnace. The slag has temperatures ranging from 1,400°C to 1,600°C, and as it comes into contact with large amounts of water, the stream of molten slag converts into a glassy material with hydraulic properties. The material is granular and can be ground into the required degree of fineness.
The addition of this slag to drilling fluids imparts cementing properties to that can be used to cement the casing string to the borehole. Once the casing point is reached, a mixture of drilling fluid, chemical activators and high concentrations of hydraulic blast furnace slag is pumped in, allowing the drilling fluid to set, creating a complete seal for the annulus.