Alumina-containing calcium silicate and process for producing same

Claim 2

Super-lightweight secondary particles of alumina-containing calcium silicate characterized in that the particles are 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 μm in diameter, up to about 0.13 g/cm 3 in apparent density and at least 10 g per particle in initial breaking load.

Claim 3

Secondary particles as defined in claim 1 wherein the alumina-containing calcium silicate crystals have an index of crystallite antigrowth of at least 10.

Claim 4

Secondary particles as defined in claim 1 wherein the alumina-containing calcium silicate crystals are needlelike crystals of alumina-containing xonotlite.

Claim 5

Secondary particles as defined in claim 1 wherein the alumina-containing calcium silicate crystals are needlelike crystals of alumina-containing xonotlite and other calcium silicate in mixture therewith.

Claim 6

An aqueous slurry of calcium silicate crystals uniformly dispersed in water, said crystals comprising super-lightweight secondary particles of alumina containing calcium silicate characterized in that the particles have 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 μm in diameter, up to about 0.13 g/cm 3 in apparent density and at least 10 g per particle in initial breaking load, said slurry being prepared by the process of claim 1.

Claim 7

An aqueous slurry as defined in claim 5 which contains a reinforcing material.

Claim 8

An aqueous slurry as defined in claim 6 which contains an inorganic fiber as joined to the secondary particles.

Claim 9

A process for preparing a uniformly dispersed product slurry of super-lightweight secondary particles of alumina containing calcium silicate in water characterized in that the particles are composed of alumina-containing calcium silicate crystals having an index of crystallite antigrowth of at least 8 and being interlocked with one another in the form of a globular shell, said particles being about 5 to about 70 μm in diameter, up to about 0.13 g/cm 3 in apparent density and at least 10 g per particle in initial breaking load, said process comprising mixing together water, a lime material and an amorphous siliceous material containing Na 2 O and K 2 O in a total amount of at least 0.5% by weight agitating the resulting mixture to obtain a mixture having 50% of the particles contained therein up to 7 μm in diameter, admixing the agitated mixture with an amount of an alumina material to provide about 1 to about 8% by weight of Al 2 O 3 calculated on the basis of the combined amount of SiO 2 and CaO contained in the siliceous material, plus the lime material plus the alumina material, the atomic ratio of silicon atoms to aluminum atoms being at least 5:1 in the lime material, plus the siliceous material plus the alumina material, to obtain a starting slurry containing at least 15 parts by weight of water per part of solids and hydrothermally reacting the starting slurry with stirring to form the product slurry.

Claim 10

A process for preparing a uniformly dispersed product slurry of super-lightweight secondary particles of alumina containing calcium silicate in water characterized in that the particles are composed of alumina-containing calcium silicate crystals having an index of crystallite antigrowth of at least 8 and being interlocked with one another in the form of a globular shell, said particles being about 5 to about 70 μm in diameter, up to about 0.13 g/cm 3 in apparent density and at least 10 g per particle in initial breaking load, said process comprising mixing together water, a lime material and an amorphous siliceous material containing Na 2 O and K 2 O in a total amount of at least 0.5% by weight agitating the resulting mixture to obtain a mixture having 50% of the particles contained therein up to 7 μm in diameter, admixing the agitated mixture with an amount of an alumina material to provide about 1 to about 8% by weight of Al 2 O 3 calculated on the basis of the combined amount of SiO 2 and CaO contained in the siliceous material, plus the lime material plus the alumina material, the atomic ratio of silicon atoms to aluminum atoms being at least 5:1 in the lime material, plus the siliceous material plus the alumina material, to obtain a starting slurry containing at least 15 parts by weight of water per part of solids and hydrothermally reacting the starting slurry with stirring to form the product slurry.

Claim 11

A process as defined in claim 8 wherein the alumina material is at least one of clay, zeolite and alumina.

Claim 12

A process for preparing super-lightweight secondary particles of alumina-containing calcium silicate characterized in that the particles have 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 μm in diameter, up to about 0.13 g/cm 3 in apparent density and at least 10 g per particle in initial breaking load characterized by drying the aqueous slurry of alumina-containing calcium crystals defined in claim 8.

Claim 13

A process for preparing a shaped body of alumina-containing calcium silicate characterized by shaping the aqueous slurry of alumina-containing calcium silicate crystals defined in claim 5 and drying the shaped mass.

Claim 14

A process for preparing a shaped body of alumina-containing calcium silicate characterized by shaping the aqueous slurry of alumina-containing calcium silicate crystals defined in claim 6 and drying the shaped mass.

Claim 15

The process of claim 8 in which the alumina-containing calcium silicate crystals comprise alumina-containing xonotlite crystals having a Ca/Si+Al atomic ratio of 0.80 to 1.3.

Claim 16

The process of claim 8 in which the alumina-containing calcium silicate crystals comprise a mixture of a major amount of alumina-containing xonotlite crystals having a Ca/Si+Al atomic ratio of 0.8 to 1.3, and a minor amount of alumina-containing tobermorite crystals.

Claim 17

The process of any one of claims 13 or 14 in which the Ca/Si+Al atomic ratio is 0.85 to 1.1.

Claim 18

A shaped body of alumina-containing calcium silicate, said shaped body being prepared according to the process of any one of claims 11 or 12, said alumina-containing calcium silicate being characterized in that the shaped body comprises super-lightweight secondary particles of alumina-containing calcium silicate jointed on one another and composed of alumina-containing calcium silicate crystals, the calcium silicate crystals having an index of crystallite antigrowth of at least 8 and being interlocked with one another in the form of a globular shell, the particles before shaping being about 5 to about 70 μm in diameter, up to about 0.13 g/cm 3 in apparent density and at least 10 g per particle in initial breaking load.

Claim 19

A shaped body as defined in claim 16 wherein the alumina-containing calcium silicate is an alumina-containing xonotlite.

Claim 20

A shaped body as defined in claim 16 wherein the alumina-containing calcium silicate is a mixture of alumina-containing xonotlite crystals and other calcium silicate crystals.

Claim 21

A shaped body as defined in claim 16 which contains a reinforcing material as uniformly dispersed therein.

Claim 22

A shaped body of β-wollastonite prepared by firing the shaped body defined in claim 16 at 800° to 1,050° C.

Claim 23

A process for preparing a shaped body of β-wollastonite characterized by firing the shaped body of alumina-containing calcium silicate defined in claim 16.