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AssigneeJ. M. Huber Corporation
InventorsGary Michael Freeman, John Mecaslin MacGeoghegan Harrison, Klaus A. Lunden
Estimating the term…
A method of significantly improving the brightness and shade properties of a high quality PCC product. The method includes providing a calcium containing feed source that contains discoloring impurities. The calcium containing feed source is formed into an aqueous slurry of calcium carbonate. Thereafter, the slurry is fine screened through a 325 mesh screen in order to yield a slurry of filler grade calcium carbonate. The filler grade calcium carbonate slurry is wet milled in order to liberate the discoloring impurities and reduce the median particle size of the calcium carbonate to less than 2 microns. The discoloring impurities are then magnetically separated from the milled calcium carbonate slurry by subjecting the slurry to a high intensity magnetic filed. After the magnetic separation step, the purified slurry may be de-watered to yield a dry powder; or alternatively, the slurry may be retained in aqueous form. In any event, the resultant calcium carbonate product has a median particle size of less than 2 microns and a TAPPI brightness of greater than 96.
A precipitated calcium carbonate product comprising a plurality of calcium carbonate particles having a median particle size of less than about 2.0 .mu.m, a TAPPI Brightness of at least about 97, and a 75/25 slope value of less than 2.0.
A method of producing a fine particulate precipitated calcium carbonate having TAAPI brightness of at least 96 comprising the steps of:
A method of producing a fine particulate precipitated calcium carbonate having TAAPI brightness of at least 96 comprising the steps of:
A method of producing a fine particulate precipitated calcium carbonate having a TAPPI brightness of greater than 96 comprising the steps of:
Dependencies are inferred from the claim text.