Abstract: The invention provides a process for producing a ceramic product for use as a construction material. According to the process of the invention, 2 to 50% by weight, based on the total weight, of sludge ashes containing 0.3 to 0.8 mole of CaO in Seger formula, 0.1 to 0.5 mole of MgO in Seger formula, and 0.2 mole or more of P.sub.2 O.sub.5 in Seger formula is added to a ceramic raw material. A desired percentage can be selected from the range of 2 to 50% to produce a ceramic product with desired properties. Also, according to the invention, a molded body can be fired at a temperature lower than a temperature used to fire a molded body with no sludge ashes to produce a ceramic product which is comparable to a ceramic product produced by firing the latter molded body. That is, according to the invention, a molded body can be fired at a temperature of 900.degree. to 1,200 .degree. C. to produce such a ceramic product.

Abstract: A process for producing a ceramic product using sludge ashes comprises the steps of (i) mixing at least ashes obtained by burning a sludge which has been obtained by the treatment of sewage and a plastic ceramic raw material to prepare a first body, (ii) mixing at least a plastic ceramic raw material and a fusible material to prepare a second body, (iii) supplying the first and second bodies into a matrix of a molding machine such that the first and second bodies form a lower, larger layer and an upper, smaller layer which covers the lower layer, respectively, (iv) molding the whole of the first and second bodies into an object with a desired shape, and (v) firing the molding to produce a two-layer ceramic product.

Abstract: The invention provides a process for producing ceramic products using, as one of the materials, the sludge obtained by sewage treatment. The invention thus not only makes the sludge treatment unnecessary, but makes the sludge useful as a material for products. A plastic ceramic raw material and, if required, another raw material are added to either the sludge or the ashes obtained by burning the sludge, so as to prepare a body. The body thus obtained is molded into a desired shape, and fired to produce a ceramic product. The firing process prevents the product, containing the sludge, from emitting an offensive odor or being decomposed. The product may be used as a tile, brick block, or the like. Production conditions such as the proportion of each raw material used and the like may be suitably selected to obtain a ceramic product with a desired characteristic in respect of water permeability, from almost no permeability to a very high permeability.