Patent GB-190504194-A (GB)
Title: Improved Process for Manufacturing Hydraulic Binding Substances or Cements.
Inventor: BOULT ALFRED JULIUS
Filed: 1905-02-28
Granted: 1906-02-28
Abstract: 4194. Boult, A. J., [Reiche, M.]. Feb. 28. Cements; stone, artificial; slags, treatment of; fire-proof compositions.-Relates to an improvement on the invention described in Specification No. 16,794, A.D. 1901, consisting in the preparation of binding-substances containing hydrate water from cement-forming oxides ground to the consistency of flour, for example, so that about 20-30 per cent only will be left on a sieve of 4400 meshes to the square inch. The oxides are mixed with basic oxides and may be converted into cements by calcination. The invention is also applicable to pigments, and, according to the Provisional Specification, to fireproof materials. The binding-substances may be used in the manufacture of artificial stone by substituting them wholly or in part for the calcium hydrate of artificial lime-sandstones and also when made of silicates, e.g. marl or clay, for assisting the fritting of Portland cement raw materials. If acids, salts, or metallic oxides suitable for forming cements are ground to flour, mixed with quicklime or calcium hydrates, and subjected to high-pressure steam so as to give basic compounds, these products will be found to act as slow binders. These hydraulic compounds mixed with sand harden in steam and, if made from silicates only, in the open air and under water. Inferior products prepared in this way are improved by exposing them to superheated steam or moist hot air at a temperature above the opening-up temperature but not sufficiently high to drive off all water. Products produced by the setting of Roman cement or of hydraulic lime with water or steam act like the above hydraulic substances as fluxes in the manufacture of Portland cement. In place of silicious substances, there may be used alumina, sesquioxides of earth metals, iron, chromium, or manganese oxides, iron ores rich in silica, zinc, copper, lead, or similar oxides, or oxides of the chromic acid series, boric, arsenic, antimonic, and stannic acids, acid and neutral salts of silicic, boric, chromic, tungstic, arsenic, stannic, antimonic, and other acids, some of these materials producing colours. The quantity of lime to be added must be calculated stoichiometrically in certain definite proportions. Examples of manufacturing mixed hydraulites are :-(1) antimony pentoxide is calcined with lead oxide in a muffle furnace until a yellow colour appears, the mixture being then steamed with calcium hydrate in a moist state ; (2) a mixture of tin oxide and copper nitrate or basic copper chromate in chromic acid may be somewhat similarly treated. Again, in place of sand there may be used calcined kaolin or clay, roasted iron ore containing clay, blast-furnace slag, fossil meal, &c., the treatment varying somewhat in detail although the extremely fine grinding is an essential. The steam product is converted into an hydraulic cement by calcination. When reducing the fritting temperature in the manufacture of Portland cement, the hydratized hydraulite may be added to, or formed in, the raw mass to the extent of 5-25 per cent. In the manufacture of artificial stone, it is advisable to use, in addition to coloured binding-substances prepared by the above-described method, steamed or calcined binders made from white silicates, such as kaolin, silicic acid, and talc.