Dravo Lime Company

Dravo Lime, Inc.

Manyam Babu

John W College

Daniel W Berisko

Shiaw C Tseng

Russell C Forsythe

Bruce W Lani

Magnesium hydroxide of high purity, having a fine particle size suitable for use in flame retardants and other high-end uses, is produced by utilizing flue gas desulfurization system process slurry as feedstock; the production process is absent energy-intensive steps as well as high-cost chemical usage.

High-purity magnesium hydroxide and process for its production

A process for removing both sulfur dioxide and nitrogen oxides from a gaseous stream where the stream is contacted in a first wet scrubbing unit with an alkaline earth compound to remove sulfur dioxide and humidify the gaseous stream, passing of the humidified gaseous stream to a coronal discharge unit to convert NO.sub.x therein to nitric acid, and then contacting the gaseous stream to a second wet scrubbing unit and contacting the gaseous stream with an alkaline earth compound to remove the nitric acid as an alkaline earth nitrate prior to discharge of the gaseous stream to the atmosphere. The effluent from the first wet scrubbing unit is maintained separate from the effluent from the second wet scrubbing unit during the removal steps so as to provide pure recoverable by-products.

Process for removing SO.sub.2 and NO.sub.x from a gaseous stream

A method of removing dioxide and nitrogen oxides from a gaseous stream where an alkaline earth compound is added, either in a wet scrubbing unit which substantially saturates the gaseous stream with water, or to a gaseous stream to which water has been added, and the gaseous stream then exposed to a coronal discharge, with dry calcium hydroxide added which reacts with nitric acid formed by the coronal discharge to form calcium nitrate. Alkaline earth sulfites or sulfates, formed by reaction of the alkaline earth compound with sulfur dioxide are removed from the gaseous stream and calcium nitrate, formed by reaction of injected dry calcium hydroxide with the nitric acid produced are separated from the gaseous stream and the gaseous stream, with sulfur dioxide and nitrogen oxides removed, is discharged to the atmosphere.

Method for removing sulfur dioxide and nitrogen oxides from combustion

Cement is produced by forming a moist mixture of a flue gas desulfurization process waste product containing 80-95 percent by weight calcium sulfite hemihydrate and 5-20 percent by weight calcium sulfate hemihydrate, aluminum, iron, silica and carbon, agglomerating the moist mixture while drying the same to form a feedstock, and calcining the dry agglomerated feedstock in a rotary kiln. Sulfur dioxide released from the calcium sulfite hemihydrate and calcium sulfate hemihydrate during calcination may be used to produce sulfuric acid, while heat recovered in the process is used to dry the agglomerating feedstock.

Process for producing cement from a flue gas desulfurization process

Sulfur dioxide is removed from a gaseous stream using an aqueous scrubbing medium containing calcium components and magnesium ions, so as to produce a more readily dewatered aqueous calcium sulfite-containing sludge by providing in the aqueous scrubbing medium in an aqueous scrubbing unit an effective amount of at least one amine sulfonate ion of the formula: ##STR1## where R is H or OH, and R' is H or SO.sub.3, with R and R' not both being H. The amine sulfonate ion is preferably provided by adding an amine disulfonate salt having the formula HN(SO.sub.3 X).sub.2 or a hydroxylamine monosulfonate salt having the formula HO--NH--(SO.sub.3 X), when X is an alkali or alkaline earth metal. Or an effluent stream from a scrubbing unit for nitrogen oxides containing a metal chelate and an amine sulfonate may be added to provide the amine sulfonate ion.

Growing community of inventors

Upper St. Clair, PA, United States of America

Manyam Babu