Ecc International Limited

Other

Imerys Minerals Limited

Ian Stuart Bleakley

Thomas R Jones

Hannu Olavi Toivonen

Jonathan Stuart Phipps

Jose M Rodriguez

Paul A Rey

Christopher Nutbeem

Philip Martin McGenity

Hannu Olavi Ensio Toivonen

A new composite material which is useful as a pigment in paper making or paper coating is produced by precipitating a white insoluble pigment compound, eg calcium carbonate, in an aqueous suspension containing a mixture of fine particulate material eg titanium dioxide particles and fibers, eg cellulosic fibers. These suspended solids in the mixture are derived from separate stocks and added together to produce the composite pigment material. The new material is a bonded matrix of the fibers and the white pigment compound having particles of the fine particulate material, eg TiO , dispersed and bonded within the matrix. The new material may exist in the form of particles in dry or wet form which may be further treated in a known way prior to use in paper making or paper coating. Use of the new material allows expensive fine particulate material such as TiO particles to be better retained in a paper making composition whilst at the same time avoiding the known problem of agglomeration or 'crowding' of the fine particles which is known to affect adversely the optical properties of the composition produced using the fine particles.

Pigment materials and their preparation and use

According to the present invention there is provided a method of treating reject from a plant for de-inking waste paper which reject comprises in an aqueous medium a mixture of suspended solids comprising at least ink particles, inorganic particles and fibers, which method includes the steps of (i) chemically treating an aqueous suspension comprising said reject by adding to the aqueous suspension a source of alkaline earth metal ions and a source of carbonate ions to react with the alkaline earth metal ions to form therein a composite particulate material comprising a substantially white insoluble alkaline earth metal carbonate compound precipitated by the said reaction which compound bonds to and entrains material comprising ink particles, inorganic particles and fibers contained in said reject, whereby the darkness of the reject is reduced by formation of the precipitate of the carbonate compound; and (ii) recovering the composite particulate material and delivering the composite particulate material for re-use as a pigment in a process for making or coating cellulosic sheet material.

Waste paper treatment process

There is disclosed a process for improving one or more properties of kaolin comprising:

Process for the treatment of an aqueous suspension comprising kaolin

There is disclosed a method for the preparation of a precipitated calcium carbonate (PCC) for use as a pigment in paper coating compositions, the method comprising the steps of (a) carbonating an aqueous lime-containing medium to produce an aqueous suspension of a PCC predominantly in a selected crystal form, (b) at least partially dewatering the PCC-containing suspension; and (c) subjecting the PCC-containing suspension to comminution by high shear attrition grinding with an attrition grinding medium. Steps (b) and (c) may be applied in either order, ie. (b) followed by (c) or alternatively (c) followed by (b). The dewatering step (b) is preferably carried out using a pressure filter device operating at a pressure of at least 5 MPa, preferably at least 10 MPa. A pH reduction step may be applied after steps (b) and (c). Also disclosed are pigments produced by the method and pigment and paper coating compositions including such pigments.

Paper coating pigments and their production and use

A method for recovery and use of a particulate waste material, i.e. inorganic and/or organic solid fines, present in an aqueous suspension, comprising the steps of:

Process for the treatment of waste material suspensions

There is disclosed a process for separating fine solids from water in the used water recovery system of a sheet forming mill, wherein the used water recovery system includes at least one stage in which an alkaline earth metal carbonate is precipitated in the aqueous suspension constituting the used water whereby the particulate material present in the used water becomes entrained in the alkaline earth metal carbonate precipitate. By the invention it is possible to recover the water and the fine solid materials which pass through the wire mesh belt of a paper or board forming machine, and optionally recycle those recovered materials.

Precipitated calcium carbonate

Recovery of water and solids in a paper mill

A method of preparing precipitated calcium carbonate which comprises slaking quicklime in an aqueous medium, passing the suspension of calcium hydroxide through a sieve having an aperture size in the range of 40 to 70 microns, carbonating the calcium hydroxide and separating the calcium carbonate from the aqueous medium in which it is suspended. The sieved calcium hydroxide is subjected to high energy, high shear agitation which is terminated prior to carbonation. During the carbonation, the suspension of calcium hydroxide is subjected to relatively lower energy and shear agitation compared to the previous high energy, high shear agitation.

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St. Austell, United Kingdom

Ian Stuart Bleakley