It is described an integrated process for the production of clinker by dry process, with treatment in continuous of by-pass dusts produced by the kiln, wherein the solid matter to treat consists of bypass dusts of a clinker production process, containing compounds of chloride, sodium, potassium and sulphur, such a process comprising the following steps: a) extraction of the bypass dusts directly from the phase of quench, without intermediate storage, at a temperature comprised between 150 and 200 C., with a moisture content varying from 0.1 to 3% by weight, preferably from 0.1 to 0.5% by weight, and with a quantity of calcium carbonate lower than 55% by weight; b) mixing of said dusts coming from step a), within a maximum time comprised between 2 and 10 minutes, preferably lower than about 5 minutes, with water up to a water/dusts ratio varying from 2:1 to 4:1, preferably from 2.5:1 to 3.5:1, in a way to obtain a mixture with a moisture content comprised between 45 and 75% by weight, preferably between 50% and 55% by weight, even more preferably equal to about 50% by weight; c) mechanical stirring of the mixture diluted up to complete dissolution of the soluble salts; d) mechanical separation of the mixture so diluted in a liquid fraction containing water and soluble salts and in a solid fraction in form of cake or crust.

A method for treating and utilizing bypass dusts from a cement production process involves a) contacting the bypass dust with an aqueous phase and mixing the same to obtain a suspension, wherein water-soluble components of the bypass dust are dissolved in the aqueous phase; b) performing a solid/liquid separation, in particular a vacuum filtration or a filter press filtration, to separate the solids contained in the suspension, wherein a brine remains; c) precipitating a partial amount of the heavy metals present in the brine, and optionally Ca, and separating the precipitate from the brine; and d) subjecting the brine to an electrocoagulation, wherein a flocculate containing the heavy metals remaining in the brine is separated.

A method for treating and utilizing bypass dusts from a cement production process involves a) contacting the bypass dust with an aqueous phase and mixing the same to obtain a suspension, wherein water-soluble components of the bypass dust are dissolved in the aqueous phase; b) performing a solid/liquid separation, in particular a vacuum filtration or a filter press filtration, to separate the solids contained in the suspension, wherein a brine remains; c) precipitating a partial amount of the heavy metals present in the brine, and optionally Ca, and separating the precipitate from the brine; and d) subjecting the brine to an electrocoagulation, wherein a flocculate containing the heavy metals remaining in the brine is separated.

A process and device separate off a volatile component from the off-gases in cement clinker production. Raw materials for cement clinker production are passed through a preheater with heat exchange with the off-gases and are then burnt in a rotary kiln. Owing to the heating in the preheater, the volatile component bound in the raw materials is vaporized and separated off. A first raw material stream having a relatively high concentration of the volatile component is applied to a first line of the preheater and a second raw material stream having a lower concentration of the volatile component is applied to a second line. The volatile component is separated off from the first substream of the off-gases. The first raw material stream heated to a temperature of at least 250 C. with the first substream of the off gases in the first line is combined with the second raw material stream.

To provide a fractionating device capable of stably fractionating powders such as cement raw materials by a simple configuration. A fractionating device 1 for fractionating some of a powder (cement raw material) R falling in a chute (main body) 2, wherein the fractionating device is equipped with a screw conveyor 5 which passes through the chute, a part of a casing 5a opening inside the chute, and receives part of the powder from an opening (inlet) 5b, and a collision separation member (collision separation rod) 4 which is provided above the screw conveyor in the chute and collides with an object when an object of a predetermined size or larger falls, and prevents the object from falling directly onto the screw conveyor. A rotation shaft 5d of the screw conveyor may be inclined from 5 to 20 with respect to the horizontal plane so that the end of the discharge port side of the screw conveyor is positioned above the other end and may be equipped with a guide member 3 that guides the powder falling in the chute in the direction of the opening of the screw conveyor.

A system and method for treating cement kiln dust is provided. The method includes the steps of receiving cement kiln dust (CKD) from a kiln; heating the collected CKD; forming a gas stream of vaporized metal and CKD by sufficient heating to separate at least one heavy metal from the collected CKD stream to create a cleaned CKD stream and a metal stream; providing a water soluble alkaline-earth metal polysulfide; combining the heavy metal stream with the water soluble alkaline-earth metal sulfide to create a combined stream; and removing at least a portion of one heavy metal from the combined stream.

Methods and apparatus for reducing the content of controlled acidic pollutants in clinker kiln emissions are disclosed. The methods and apparatus include introducing bypass dust produced during production of clinker into one or more locations between the preheater exhaust and the inlet to a dust filter including into a gas conditioning tower. Total bypass dust separated from the kiln exhaust gas may be used. The bypass dust can be separated into a fine and coarse portions. Fine or total bypass dust can be mixed with water to form a bypass dust slurry that can be introduced into the gas conditioning tower. Bypass dust can be used to reduce the content of acidic pollutants such as hydrogen chloride HCl and sulfur oxides SO.sub.x from clinker kiln emissions.

A method for cleaning bypass gases of the cement or mineral industry includes cooling down a removed bypass gas from a cement or mineral processing plant to a temperature of between 500 C. and 150 C., and coarsely dedusting the bypass gas, the dust burden being reduced by 30 to 95%. After the dedusting step, the gaseous constituents contained in the partly dedusted bypass gas are reduced in a reducing step. The partly dedusted bypass gas is further finely dedusted. The gaseous constituents reducing step includes at least a catalytic reduction of one or more of nitrogen oxides, hydrocarbons, and carbon monoxide.

Methods and apparatus for reducing the content of controlled acidic pollutants in clinker kiln emissions are disclosed. The methods and apparatus include introducing bypass dust produced during production of clinker into one or more locations between the preheater exhaust and the inlet to a dust filter including into a gas conditioning tower. Total bypass dust separated from the kiln exhaust gas may be used. The bypass dust can be separated into a fine and coarse portions. Fine or total bypass dust can be mixed with water to form a bypass dust slurry that can be introduced into the gas conditioning tower. Bypass dust can be used to reduce the content of acidic pollutants such as hydrogen chloride HCl and sulfur oxides SO.sub.x from clinker kiln emissions.

Methods and apparatus for reducing the content of controlled acidic pollutants in clinker kiln emissions are disclosed. The methods and apparatus include introducing bypass dust produced during production of clinker into one or more locations between the preheater exhaust and the inlet to a dust filter including into a gas conditioning tower. Total bypass dust separated from the kiln exhaust gas may be used. The bypass dust can be separated into a fine and coarse portions. Fine or total bypass dust can be mixed with water to form a bypass dust slurry that can be introduced into the gas conditioning tower. Bypass dust can be used to reduce the content of acidic pollutants such as hydrogen chloride HCl and sulfur oxides SO.sub.x from clinker kiln emissions.