This application discloses exemplary processes and systems for reducing mineral ring accumulation in calcination kiln. The processes and systems comprise inserting non-condensable gases (“NCGs”) in a preheating zone of a calcination kiln, upstream of the burner end. The pre-heating zone may be characterized by temperatures ranging from 1,300° F. to 1,750° F. The system may desirably comprise a plenum for inserting the NCGs into the rotating calcination kiln at the pre-heating zone.

In a known method for treating pourable, inorganic grain, a heated rotary tube is used that rotates about an axis of rotation and surrounds a treatment chamber that is divided into a plurality of treatment zones by means of separating elements. The grain is supplied to the treatment chamber at a grain inlet side and is transported, in a grain transport direction, to a grain outlet side and is exposed to a treatment gas in the process. In order, proceeding herefrom, to allow for reliable and reproducible thermal treatment of pourable inorganic grain, in particular SiO.sub.2 grain in the rotary kiln, in a manner having low and effective consumption of treatment gas, it is proposed for spent treatment gas to be suctioned out of a reaction zone of the treatment chamber, by a gas manifold that rotates about the longitudinal axis thereof.

In the disclosed solution sand to be cleaned is thermally cleaned by rotating the sand being cleaned in a large oven (1) by rotating the oven (1). Before cleaning, the sand may be pre-processed by crushing any lumps and cleaning the sand fraction by magnetic separation. Preprocessed sand to be cleaned and heat energy are fed (5) into the rotating oven. The oven (1) is set slightly inclined so that a second end of the oven (1) is lower than a first end. The inclination and rotating speed of the oven (1) as well as the feed amount of sand are adjusted, whereby the advancing speed of the sand may be adjusted, as well as the ratio of the sand being cleaned to the volume of the oven (1) kept as desired. The temperature of the oven (1) is monitored at the coldest area of the oven, which is substantially at the second end of the oven. The temperature of the oven (1) is adjusted by adjusting the amount of heat energy fed in. By means of temperature monitoring and knowing the advancing speed of the sand, it is also possible to determine the average temperature of the sand and adjust it as desired by adjusting the supplied heat energy. Finally, the cleaned sand is let run (12) from the second end of the oven (1).

Processes and plants for producing cement clinker, in which an oxygen-containing gas having a proportion of 15% by volume or less of nitrogen and a proportion of 50% by volume or more of oxygen is conveyed from a first section of the cooler directly adjoining the top of the furnace into the rotary furnace and is optionally additionally conveyed to the calciner, and where the total gas streams fed in to the combustion processes consist to an extent of more than 50% by volume (preferably more than 85% by volume) of oxygen.

The object of the present invention is to improve production efficiency of lithium hydroxide anhydride in a method for producing lithium hydroxide anhydride from lithium hydroxide hydrate by using a rotary kiln. The method for producing lithium hydroxide anhydride comprises steps of: supplying the lithium hydroxide hydrate to a region between a heating part which is the part of the furnace core tube surrounded by the heating furnace and one end of the furnace core tube; delivering the supplied lithium hydroxide hydrate toward the other end of the furnace core tube; feeding a drying gas with a temperature of 100 C. or higher to the region between the one end and the heating part of the furnace core tube, when the lithium hydroxide hydrate is supplied; and heating and dehydrating the lithium hydroxide hydrate by the heating furnace which is set to 230-450 C. during the lithium hydroxide delivering step, to form lithium hydroxide anhydride.

The invention relates to an aluminum scrap melting system (1) comprising a melting furnace (10) comprising a burner (20) which comprises an oxidant injector (23), and a fuel injector (25); a suction hood (30) intended to capture by suction the combustion fumes (F) and comprising a carbon monoxide sensor (37) configured to measure a carbon monoxide concentration (C) in said combustion fumes (F); and a control device (50) configured to receive an item of input information representative of the value of the carbon monoxide concentration (C), and to pilot the oxidant injector (23) and/or the fuel injector (25), according to said item of input information, the oxidant and fuel flows being piloted to contain the volatile organic compound content (VOC) at the output of the melting furnace at concentrations less than a safety value. The invention also relates to a process for melting aluminum scrap with such a melting system (1).

Method of operating a long direct-fired inclined counterflow rotary kiln for the thermal treatment of material and counterflow rotary kiln adapted for same, whereby material to be treated is introduced into the kiln at the inlet end and treated material is evacuated from the kiln at the outlet end, whereby a main combustion zone extends inside the kiln over a distance of to of the internal length L.sub.int of the kiln, whereby a supplementary combustion zone in which supplementary combustion takes place with an oxygen-rich oxidant extends inside the kiln over a distance from the inlet end of at most of the internal length L.sub.int, and whereby no combustion takes place in a heat exchange zone located between the main combustion zone and the supplementary combustion zone.

This application discloses exemplary processes and systems for reducing mineral ring accumulation in calcination kiln. The processes and systems comprise inserting non-condensable gases (NCGs) in a preheating zone of a calcination kiln, upstream of the burner end. The pre -heating zone may be characterized by temperatures ranging from 1,300 F. to 1,750 F. The system may desirably comprise a plenum for inserting the NCGs into the rotating calcination kiln at the pre-heating zone.

A directional fluid heat control system for a high temperature kiln with a process zone. The system includes two rigid, coaxially aligned tubes positioned in the kiln. One tube rotates inside the other. One tube has a series of longitudinal openings, while the other has a series of helically arranged openings. Rotating one tube selectively aligns an opening from that tube with an opening in the other. Further rotation aligns different such pairs of openings with different longitudinal orientations in the kiln. The aligned openings release pressurized fluid from the inner tube into desired locations in the kiln's process zone.

A gas inerting system and method is provided. This system includes a rotary melting furnace with a furnace barrel, a burner, and a charge of metal to be melted; and an injection manifold with a plurality of injection orifices. The burner is configured to produce a flame directed into the furnace barrel, and the plurality of injection orifices are configured to disperse inert gas streams into the furnace barrel, into an inerting region between the burner flame and the charge of aluminum. The metal to be melted may be aluminum. The method of inerting includes rotating the rotary furnace and introducing heat into the furnace barrel by generating the flame, thereby beginning a melt cycle, then introducing the inert gas streams into an inlet to the injection manifold, thereby directing the inert gas streams through the injection orifices and into the inerting region, after a predetermined condition has been met.