Abstract: A board of calcium silicate crystals, characterized in that the board is composed of a plurality of layers of laminated thin sheets, each of the thin sheets having a thickness of 2 mm or less, each layer comprising secondary particles of calcium silicate crystals, a fibrous material, a coagulant and preferably additionally a polymer adsorbed on the surface of the secondary particles of calcium silicate; wherein each layer contains secondary calcium silicate particles interconnected with one another, and wherein the superposed thin sheets are firmly united with one another into an integral body by the interlayer interconnection of secondary particles of calcium silicate crystals present on the surface of the sheets.

Abstract: A board of calcium silicate crystals, characterized in that the board is composed of a plurality of layers of laminated thin sheets, each of the thin sheets having a thickness of 2 mm or less, each layer comprising secondary particles of calcium silicate crystals, a fibrous material, a coagulant and preferably additionally a polymer adsorbed on the surface of the secondary particles of calcium silicate; wherein each layer contains secondary calcium silicate particles interconnected with one another, and wherein the superposed thin sheets are firmly united with one another into an integral body by the interlayer interconnection of secondary particles of calcium silicate crystals present on the surface of the sheets.

Abstract: A silica shaped body comprising a multiplicity of interconnected secondary particles of amorphous silica, voids interspersed between the secondary particles, and at least one inorganic inactive substance selected from among carbonaceous substance, carbide, nitride and metallic oxide and physically united with the secondary particles, is prepared by containing a siliceous material, calcareous material and water to a hydrothermal synthesis reaction with heating and stirring under an elevated pressure to obtain an aqueous slurry of secondary particles of calcium silicate crystals, followed by carbonation, shaping and drying.

Abstract: A calcium silicate shaped body which comprises a multiplicity of interconnected secondary particles of calcium silicate crystals, voids interspersed between the secondary particles, and at least one inorganic inactive substance selected from among carbonaceous substance, carbide, nitride, silicide and metallic oxide which is physically united with the secondary particles, the shaped body containing the inactive substance in an amount of 21 to 70% by weight; and a calcium silicate shaped body which comprises a multiplicity of interconnected secondary particles of calcium silicate crystals, voids interspersed between the secondary particles, and at least one inorganic inactive substance selected from among carbonaceous substance, carbide, nitride, silicide and metal oxide and physically united with the secondary particles, and an amorphous siliceous substance.

Abstract: Amorphous silicas having a crystalline appearance, at least two surfaces in symmetric relation, a length of about 1 to about 500.mu. and a thickness of about 50 A to about 1.mu., the length being at least about 10 times the thickness, the amorphous silicas being in the form of primary particles, secondary particles, aqueous dispersions of the particles and shaped bodies.

Abstract: Globular secondary particles of wollastonite group calcium silicate crystals represented by the formulalCaO.mSiO.sub.2.nH.sub.2 Owherein 1.ltoreq.l.ltoreq.6, 1.ltoreq.m.ltoreq.6 and 0.ltoreq.n.ltoreq.1, characterized in that the particles comprise hollow globular secondary particles of the wollastonite group calcium silicate crystals, the globular secondary particles having an average spontaneous sedimentation height of at least 800 ml, an outside diameter of 5 to 110 .mu.m, an average apparent density of 0.04 to 0.09 g/cm.sup.3 and an average shell density defined by the equationY=0.0033X+Bwherein Y is the average shell density, X is the average diameter of the particles, B is a constant, 15 .mu.m.ltoreq.X.ltoreq.40 .mu.m and 0.ltoreq.B.ltoreq.0.115.

Abstract: Alumina-containing calcium silicate being in the form of secondary particles, shaped bodies and a process for preparing the same, said secondary particles being composed of alumina-containing calcium silicate crystals having an index of crystallite antigrowth of at least 8 and interlocked with one another in the form of a globular shell, the particles being about 5 to about 70 .mu.m in diameter, up to about 0.13 g/cm.sup.3 in apparent density and at least 10 g per particle in initial breaking load, and said shaped bodies being composed of the secondary particles.

Abstract: Amorphous silicas having a crystalline appearance, at least two surfaces in symmetric relation, a length of about 1 to about 500.mu. and a thickness of about 50 A to about 1.mu., the length being at least about 10 times the thickness, the amorphous silicas being in the form of primary particles, secondary particles, aqueous dispersions of the particles and shaped bodies.

Abstract: A shaped body of calcium silicate characterized by being composed of globular secondary particles interconnected with one another and each made up of lath-like xonotlite or foshagite crystals having been three-dimensionally interlocked with one another and having an index of crystallite antigrowth of at least 15, the globular secondary particles having had an outside diameter of about 10 to about 80 .mu.m and an apparent density of up to 0.13 g/cm.sup.3 and having been in the form of a shell with a hollow interior space and a thickness of about 0.3 to about 10 .mu.m before being shaped into the body.

Abstract: An apparatus for molding a slurry of calcium silicate crystals comprising: a base plate provided with drain passages on the upper surface; a net conveyor having meshes for dewatering the slurry and disposed on the upper surface of the base plate in contact therewith; a frame-shaped lower mold placed on the net conveyor and immediately above the base plate; an upper mold provided on the low surface thereof with dewatering means for dewatering the slurry and movable into the lower mold to press and dewater the slurry in cooperation with the lower mold and to thereby form a shaped product; drive means for raising and lowering the lower mold; drive means for raising and lowering the upper mold; and lower mold holders movable with the upper mold and also movable upward and downward independently of the upper mold.