Abstract: A method and apparatus for calcining lime, dolomite or similar materials in which the raw material to be calcined is preheated in a preheating zone by exhaust gases from a calcining zone, cooled by means of combustion air in a cooling zone, the combustion air passing from said cooling zone into said calcining zone and then into the preheating zone. A specific improvement of the invention resides in adding fuel in the calcining zone at a plurality of spaced locations along the calcining zone in the direction of flow of the combustion air therethrough.

Abstract: A causticization method including the steps of calcining limestone in the presence of additive means for producing lime of increased lime efficiency relative to the lime that would result from calcining such limestone without the presence of the additive means, lime efficiency being determined on a sodium carbonate solution for which conditions, other than the character of the lime, are fixed, and subsequently feeding the lime of increased lime efficiency into the sodium carbonate solution for producing sodium hydroxide and calcium carbonate from the sodium carbonate.

Abstract: A method and apparatus for calcining minerals, particularly limestone, in a shaft kiln having at least two vertically spaced levels including cooled hollow supports through which a solid fuel is introduced into the kiln. One feature of the present invention resides in employing a granular coal as the fuel while other features are involved with the distribution of fuel between various inlet points, suspension of the fuel in an airstream, and the mechanical construction of the fuel conduits and their support located within the shaft kiln.

Abstract: Biomass residue is added at the cold end of a rotary calcination kiln to generate heat in situ thereby diminishing substantially the amount of fossil fuel normally fired at the hot end of the kiln.

Abstract: Calcination of limestone to form a finely divided lime product without substantial contamination by impurities (especially carbon and ash) is accomplished in a secondary fluidized bed with reaction heat provided by recirculating entrained particles from a primary multisolid fluidized bed combustor.

Abstract: A process of making different grades of calcium magnesium acetate deicing agents, having substantially uniform but different calcium-to-magnesium mole ratios, from limestone having varying proportions of calcium carbonate and magnesium carbonate, is provided wherein limestone containing calcium and magnesium carbonates is finely divided, mixed with water to form an aqueous suspension of limestone, vigorously agitated and reacted with excess acetic acid. The reaction is completed by adding to the reaction batch about 30% of the molar equivalent of calcined finely divided limestone base to produce a calcium magnesium acetate salt solution having a calcium-to-magnesium mole ratio much greater than one. The insolubles from this first reaction are removed, calcined and reacted with acetic acid in a second reaction to produce a calcium magnesium acetate salt solution having a calcium-to-magnesium mole ratio substantially equal to one.

Abstract: An already existing conventional lime production plant using a rotary kiln discharging directly into a rotary cooler, is converted reversibly to the production of dry hydrated lime by introducing water into contact with the lime in the cooler sufficient to hydrate the lime without requiring any significant change in the operating parameters of the lime production such as material throughput, cooling and combustion air supply rates and firing conditions.

Abstract: A regenerative shaft furnace for burning carbonate-containing raw materials is disclosed having two or more shafts which are interconnected by ducts which operate in an alternate manner and wherein the burned raw material is cooled in the cooling zone of the shafts. Having a displacer in the cooling zone to prevent the reabsorption of carbon dioxide in the fuel gases by the burned material. A method for burning carbonate-containing raw material is also disclosed.

Abstract: A process is disclosed for producing quicklime by a calcining treatment with a hot gas in a rotary kiln, wherein solid carbonaceous fuel for producing hot gas is fed into the charging end of the rotary kiln and an oxygen-containing gas is blown through nozzle blocks into the charge disposed over nozzle blocks in the heating-up zone beginning at the point where ignitable particles of the solid fuel first appear, the improvement wherein:(a) an oxygen-containing gas is blown through nozzle blocks into the charge disposed over nozzle blocks in that region of the heating-up zone which begins with the appearance of ignitable particles of the solid fuels and which ends where the temperature in the charge does not rise further;(b) oxygen-containing gases are blown through nozzle blocks into the charge disposed over nozzle blocks in a calcining zone which succeeds said heating-up zone and at such a rate that the temperature in the charge is held constant and for as long as the temperature remains constant,(c) oxygen-c

Abstract: Disclosed is a method of thermal treatment of a carbonate suspension yielding lime and CO.sub.2 -containing gas, such suspensions may be those resulting from a filtration sediment for sugar production, comprising in general the steps of dividing the carbonate suspension into two portions, spray-drying these portions both simultaneously and independently, calcining the material produced after suspension drying, cooling the lime produced after calcination, supplying the gas from the calcination zone for spray-drying the first portion of the suspension, withdrawing carbon dioxide recovery from the spent gas after spray-drying the first portion of the suspension, the calcination being carried out by means of the heat of the heat-carrier required for calcinating the material and spray-drying only the first portion of the suspension.

Abstract: Either sulphur-containing raw materials or sulphur-containing fuels may be used in the calcination of mineral raw materials in a calcining furnace, with significant desulphurization of the calcined material being achieved if, on the one hand, cooling air introduced into the cooling zone of the furnace is removed at the upper end of the cooling zone thereof through exhaust ducts and if, on the other hand, the flue gases are free of oxygen and have a carbon monoxide content of 1 to 5% by volume. In order to obtain this composition of the flue gases, the combustion process can either be performed in the calcining zone of the calcining shaft of the furnace with a deficiency of air or a gaseous, liquid or solid fuel can be supplied by means of fuel tubes located at a transfer duct between the furnace shafts.

Abstract: Process for the burning of lime, cement or other lumpy bulk materials in a shaft kiln using coal. Coal dust or particulated dry coal is continuously fed into a gasification chamber positioned in the center of the shaft kiln and is therein partially or fully gasified by the addition of air in substoichiometric proportions. The partially or fully gasified fuel is mixed with air at an elevated temperature. Such mixture is then burned in the burning zone of the shaft kiln. The flow of the heating medium, i.e., the burnt fuel, and the flow of the kiln charge are co-current within the kiln. The shaft kiln has a centrally postioned gasification chamber which is mounted on radial supports which are positioned in the shaft kiln in such a way as to produce a space below the supports. The space is substantially free from kiln charge. Uniform distribution of the gases is guaranteed across the cross section of the shaft kiln by the space.

Abstract: A calcining installation of improved thermal efficiency comprises a long rotary tubular kiln having an upstream inlet, a downstream outlet and an air inlet at the downstream end. A burner is positioned in the upstream half of the kiln, the upstream part of the kiln constituting a calcining zone and the downstream kiln part constituting a cooling zone for the calcined material. A cyclone separator for separating dust from the kiln flue gases has an inlet and a dust outlet, and an additional cyclone separator has an inlet, a gas outlet and a material outlet connected to the upstream end of the kiln. A pipe connects the gas outlet of the additional cyclone separator to the inlet of the cyclone separator, the pipe having a vertical portion and an inlet for the raw material in the lower part of the vertical portion.

Abstract: A process for the calcining of limestone or hydrated lime by thermal treatment thereof with hot gases in an oxidizing atmosphere in a rotary kiln through which the kiln atmosphere and the charge are countercurrently passed, which kiln is fed with fuel from shell burners, is described. The invention resides in the use of different fuels which release different quantities of SO.sub.2 and SO.sub.3 per unit of calorific heat. The fuel which releases the larger quantity of SO.sub.2 or SO.sub.3 per unit value of calorific heat is supplied to the upper portion of the rotary kiln, and the fuel which releases the smaller quantity of SO.sub.2 and SO.sub.3 per unit of calorific heat is supplied to the lower portion of the rotary kiln.

Abstract: This invention relates to a countercurrent combustion method and apparatus for the production of calcined lime in a furnace which contains, in sequence, at least one preheating zone, combustion zone, and a cooling zone. The entire combustion air is passed through the cooling zone thereby to preheat the same. A portion of the thus preheated air is withdrawn from the furnace and heated in a recuperation zone which may be within or outside the vertical shaft furnace but is located between the preheating zone and the combustion zone. In the recuperation zone, the air is heated to approximately the deacidification temperature and then is supplied to the combustion zone.

Abstract: A method and apparatus for calcining limestone in which limestone is burned continuously in a vertical kiln provided with at least one fuel injector which permits pulsed introduction of fuel thereto. Combustion air is passed continuously through the kiln and air/fuel mixing efficiency is enhanced by the use of an arch or hood superposed above the fuel injectors to thereby create a protected space in the mass of charged limestone.

Abstract: A process for the preparation of magnesium compounds from breunnerite or from mineral concentrates or tailings containing breunnerite in which the mineral is calcined and treated with an acid and the magnesium salt solution so formed is separated from insoluble matter.

Abstract: Fine solid material is preheated in a first zone, then heated to the final treatment temperature by passing it through a flame in a second zone, and then separated in a third zone from the hot exhaust gases leaving the second zone. The separated exhaust gases are led to the first zone for preheating the material. A fuel feed stock is gasified to produce a combustible gas, and such gas is burned in the second zone to produce said flame.

Abstract: A process and apparatus for burning limestone to produce calcined lime in which limestone is burned continuously in a vertical kiln provided with a plurality of fuel injectors which permit pulsed introduction of fuel so as to ensure a lamellar flow of fuel through the kiln and a controlled release of heat.

Abstract: Chemical and aqueous components of sludge derived from lime treatments of raw water supplies are recovered by procedures involving carbonation of the sludges to effect a phase separation between magnesium and calcium components. When the magnesium content of the raw water is intolerable in the treated water, a magnesium carbonate is recovered from the liquid phase by its decarbonation, and the aqueous component of the liquid phase is recycled to recover the water values of the treated sludge. When the magnesium content of the raw water can be tolerated in the treated water, the liquid phase magnesium bicarbonate solution is recycled to the water treatment plant.

Abstract: Pellet-shaped calcium hydroxide forming part of the mixture of flux and ores in electrothermal calcium carbide furnaces is calcined. The pellets are made by granulating or briquetting moist calcium hydroxide, delivered to a sintering grate and conveyed thereon through a heating zone, wherein high temperatures are produced by the combustion of gas, above the grate, and wherein the combustion gas is exhausted, below the grate. The calcium hydroxide pellets are more especially placed on to the grate, covered with a layer of broken limestone and the undried pellets are directly conveyed through the heating zone, in an apparatus for carrying out the process.

Abstract: Reactive calcium oxide is produced on an industrial scale by decomposing calcium carbonate having a grain size of less than 200 .mu.m at a temperature of at least 850.degree. C and at a CO.sub.2 --partial pressure of not more than 40% of the CO.sub.2 --equilibrium pressure corresponding to the formation of the reactive calcium oxide.