Abstract: A thermally stable steelmaking slag is produced which is suitable for use in applications requiring dimensional stability, e.g. as aggregate in road construction. Fine particles of slag obtained from a basic oxygen furnace operation or from an arc furnace operation is firstly subjected to a thermal hydration at a temperature in the range of about 100.degree. to 400.degree. C. Thereafter, the hydrated slag particles are carbonated in the presence of carbon dioxide at a temperature in the range of about 500.degree. to 900.degree. C., whereby substantially all free calcium oxide in the slag particles is converted to calcium carbonate. The product obtained is well suited for road construction and cementitious applications.

Abstract: A modification to thermogravimetric analyzers with data acquisition devised to allow concurrent TG (thermogravimetry) and DTA (differential thermal analysis) measurements employs three samples mounted close to each other in a TG furnace. Two of the samples are active ones, i.e. of the material to be analyzed, and the third is a reference sample of an inert material. The first active sample is suspended from the beam of a thermobalance. The change in weight of this sample is recorded and plotted versus the temperature of the second active sample. The sample thermocouple and another identical thermocouple are placed in contact with crucibles containing the second active sample and the reference material, respectively. The differential temperature between the sample and the reference material is taken from the two identical thermocouples. The differential signal is amplified and plotted against the temperature of the second active sample.