An investigation of the silica deposits of southern Illinois . nd alumina were added by diss-olving FeCl3 and AICI3 in the water used for making the mixture workable. TheCr203was added as Cr(N03)2 in a similar manner. After thoroughly mixing themixtures, an excess of NH^OH was added to precipitate the metals as hydroxideswhich v/ould become oxides upon drying and firing. The purpose of this was toobtain the greatest degree of distribution of the bonding agents, thereby in-creasing their fluxing action upon the silica. The other materials, (powderedand passed through a 100-mesh sieve) were adde
An investigation of the silica deposits of southern Illinois . nd alumina were added by diss-olving FeCl3 and AICI3 in the water used for making the mixture workable. TheCr203was added as Cr(N03)2 in a similar manner. After thoroughly mixing themixtures, an excess of NH^OH was added to precipitate the metals as hydroxideswhich v/ould become oxides upon drying and firing. The purpose of this was toobtain the greatest degree of distribution of the bonding agents, thereby in-creasing their fluxing action upon the silica. The other materials, (powderedand passed through a 100-mesh sieve) were added dry and mixed well with theraw materials before the addition of water. The action of the ferric hydroxide and aluminum hydroxide binders in work-ing was much different from the rest. The water containing the salts of the twometals, when added to the dry material was sufficient to make the mixture work-able. Upon addition, of 15cc. of concentrated NH^OH the mixture too stiff to be worked or molded into trial pieces. Y/ith a little puggin. 17. or working of the mass by hand, the nixture reached asoft mud consistencyand would flow readily, even though no v/ater was added, after the addition ofthe NH4OH. This was probably due to the gelatinous precipitates of FeCOH)^ andA1(0H)2. When they first formed, they cause the mixture to become stiffer dueto their colloidal character and continuous structure throughout the further mixing or pugging, the excess NH^OH acted upon these to make themmore fluid, as all alkalies act upon colloids. This action is similar to thatof using alkalies in mixing up clay slips for casting. The probability of theNH^OH acting upon the silica was slight because of the short time in which thisoccurred. With chromium nitrate, the mass was-kneaded by hand very slightly,after adding the NH^OH, thus avoiding the action of the excess alkali upon thecolloidal precipitate of Cr(0H)3. The various samples with binders v/ere then made up i
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectminesandmineralresou
