Patent GB-1361027-A (GB)
Title: Manufacture of foundry moulds or cores
IPC: B22C1/18
Filed: 1971-07-05
Abstract: 1361027 Producing foundry moulds CENTRE TECHNIQUE DES INDUSTRIES DE LA FONDERIE WENDEL-SIDELOR and INDUSTRIES CHIMIQUES DE VOREPPE 5 July 1971 [7 July 1970] 31365/71 Heading C3N A method for producing foundry moulds and cores having a high mechanical resistance comprises mixing a liquid, a refractory sand, an alkali metal silicate as a binding agent, either a blast furnace slag, a ferro-chromium slag or a cement as setting agent which reacts with the binding agent without evolution of gas and a surface active agent to form a self-hardening liquid sand and pouring this liquid into a mould, wherein the surface active agent used produces a foam which begins to subside before the sand begins to set and is at least one compound whose aqueous solutions fulfil the two following experimental criteria, (a) they have a section of stretching of the sheet of maximum length, for molar concentrations of the surface active agent of between M/5 and M/50; and (2) they give a foam whose volume is reduced by at least half in 5 minutes for a molar concentration of M/20. The method of evaluating criteria (a) is described. The density of the sand may be increased still more by applying to the sand pressure and/or repeated mechanical stresses by vibrations and agitation between the time when the sand becomes permeable and the time when it begins to set. The surface active agent may be a mixture of two or more alkylbenzene sulphonates of formula (1) wherein Me represents alkali metal or HX (X being an amine), and R 1 , R 2 , R 3  each represents an atom of hydrogen or a linear or branched alkyl group (C 1 -C 6 ) used in the amount 0À005-2% by weight based on the total weight of the liquid sand. Alternatively there may be used an alkylbenzene sulphonate of formula (I) used alone wherein R 1  is hydrogen, R 2  is hydrogen or alkyl (C 2 , C 3  or C 6 ), and R 3  is alkyl (C 2 , C 3 , C 6 ). The sand may be silica sand. Specific examples refer to the use of (a) blast furnace slag and either:-sodium mono-isopropylbenzene sulphonate (1), sodium di-isopropylbenzene sulphonate (2), a mixture of sodium mono-isopropylbenzene sulphonate and sodium di-isopropylbenzene sulphonate (3), a mixture of sodium di-isopropylbenzene sulphonate and potassium p-toluene sulphonate (4), a mixture of sodium tri-isopropylbenzene sulphonate and potassium p-toluene sulponate (5), sodium diethylbenzenesulphonate (6), sodium p-propylbenzene sulphonate (7), sodium n-hexylbenzene sulphonate (8); a mixture of sodium n-butylbenzene sulphonate and potassium p-toluene sulphonate (9), sodium octyl sulphate (10), a mixture of sodium octyl sulphate and sodium benzene sulphonate (11), a mixture of sodium mono-isopropylbenzene sulphonate, sodium diisopropylbenzene sulphonate and potassium p-toluene sulphonate (12); (b) ferro-chromium slag and a mixture of sodium di-isopropylbenzene sulphonate and sodium mono-isopropylbenzene sulphonate (13); and (c) Portland cement and sodium di-ethylbenzene sulphonate. Example 15 refers to a composition comprising new and regenerated sand, blast furnace slag, sodium silicate, and a mixture of sodium diisopropyl benzene sulphonate, sodium di-ethyl benzene sulphonate and potassium p-toluene sulphonate.