Basf Corporation

Rodney G Schroeder

Thomas E Donegan

Anand S Sharangpani

Matthew K Wong

In accordance with the instant invention red transparent iron oxide pigment is prepared from yellow transparent iron oxide pigment filter cake by drying and calcining in a single operation using a spray dryer employing a nozzle of the two fluid design.

Transparent iron oxide pigments

An apparatus for purifying copper phthalocyanine pigment in a continuous process without the use of acid. This apparatus comprises a container for preparing a slurry of said pigment in water, a pump and a conduit for conducting the slurry from the container to the inlet of the pump, a first heating apparatus capable of heating the slurry to a temperature of at least about 75.degree. C., a conduit for conducting the slurry from the pump to the first heating apparatus, a thin film pressure filter, and a conduit for conducting the slurry from the first heating apparatus to the thin film pressure filter. The apparatus is arranged such that the temperature of the slurry passing through the thin film pressure filter is close to the exit temperature of the slurry from the first heating apparatus. A product outlet is provided for the filter and a control valve is positioned in the product outlet. The apparatus includes structure for washing filter cake comprising a source of wash water, a pump, and a conduit from the source of wash water to the inlet of the pump, heating device, and a conduit for conducting wash water from the outlet of the pump to the heating device. The heating device has sufficient capacity to provide wash water at a temperature approaching that of the slurry entering the filter. A conduit is provided for conducting the wash water from the heating device to the thin film pressure filter. The apparatus also includes control apparatus adapted to control the speed of both motors on both pumps in turn controlling the pressure of the slurry entering the filter and the pressure of the wash water entering the filter.

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Holland, MI, United States of America

Rodney G Schroeder