Showing papers on "Rotary kiln published in 1970"

Hydrogen chloride recovery incinerator for plastics containing hydrogen and chlorine

Abstract: An apparatus for the disposal of scrap vinyl polymers containing chlorine and hydrogen. The apparatus includes a rotary kiln that is adapted to receive said scrap plastic and heat the same to a temperature at which the plastic partially decomposes, and the major portion of the chlorine escaping therefrom as hydrogen chloride gas, which gas together with any chlorine which results from the decomposition is recovered in a confined space for subsequent usage.

Heat processing of minerals

Abstract: Heat processing apparatus of the type including a rotary kiln, drying and preburning sections at the material inlet end to pretreat the material prior to burning in the kiln, and a cooler at the discharge end of the kiln. The drying section is divided into two in-series chambers, with hot gases from the preburning section circulated through the first such chamber and from the cooler through the second chamber.

Control system for cement kiln

Abstract: This invention relates to the combination of a rotary kiln for sintering raw material into sinter and having drive means connected to the rotary kiln for rotating the rotary kiln, heating means disposed adjacent one end of the rotary kiln for directing a heated fluid through the rotary kiln to sinter the raw material as the raw material passes through the rotary kiln from the other end of the rotary kiln to the one end of the rotary kiln, and control means associated with the rotary kiln for controlling the operation of one of the drive means and the heating means.

Rotary kiln nose ring

Abstract: A rotary kiln metallic nose ring extends about the kiln discharge end, the ring forming a series of circularly spaced ports sized and directed to pass sufficient cooling gas into the zone adjacent the kiln discharge end for flow adjacent the exposed extent of the ring as to prevent excessive heating of the ring.

Rotary kiln control apparatus and programming

Abstract: Rotary kiln operation is controlled so as to result in satisfactory kiln performance and high quality clinker production over long periods of time. Main burner fuel supply is controlled when the maximum temperature of materials in the kiln is in one range, and kiln speed of rotation is controlled when such maximum temperature is in another range. Also, air is passed to the kiln via a clinker cooler, for preheating, and the cooler speed of movement is controlled in relation to kiln speed of rotation and raw mix feeder speed.

Method of producing reduced iron ore pellets

Abstract: REDUCED IRON ORE PELLETS HAVE BEEN PRODUCED BY A METHOD WHICH COMBINES THE USE OF INTERNAL AND EXTERNAL SOLID REDUCTANTS, AND IS CARRIED OUT IN CONJUCTION WITH A GRATE KILN PROCESS. GREEN PELLETS WHICH ARE GLOBULES OF FINE GROUND ORE, BINDERS, AND INTERNALLY APPLIED SOLID REDUCTANTS, ARE PELLETIZED. THESE PELLETS ARE PREHEATED AND HARDENED ON A TRAVELLING GRATE USING WASTE GASES FROM A ROTARY KILN. THE PREHEATED AND HARDENED PELLETS ARE DISCHARGED INTO THE ROTARY KILN AND EXTERNAL SOLID REDUCTANTS ARE SIMULTANEOUSLY CHARGED, SO THAT THE PELLETS MAY BE SUBJECTED TO THE COMBINED ACTION OF THE INTERNALLY AND EXTERNALLY APPLIED SOLID REDUCTANTS. THE PELLETS HAVE GOOD PHYSICAL PROPERTIES AND SUFFICIENTLY HIGH CRUSHING STRENGTH TO PERMIT THEM TO WITHSTAND DESTRUCTIVE AND ABRASIVE ACTIONS TO WHICH THEY ARE SUBJECTED DURING OPERATION. THE PRESENT METHOD IS ECONOMICALLY EFFECTIVE TO PRODUCE HIGHLY METALLIZED PELLETS ON A MASS PRODUCTION BASIS.

Gas delivery manifold and processed material discharge assembly for rotary kiln

Abstract: A rotary kiln is disclosed with a rotary firing hood mounted concentrically over the material discharge end of the kiln to rotate with the kiln. A main burner assembly projects axially through a neck formed by a rear wall of the hood and a plurality of burners project radially through the kiln shell. Fuel gas conducting tubes for supplying the kiln shell burners, are mounted on the outer periphery of the kiln shell and extend axially through the hood and rear wall thereof. The fuel tubes each have portions that project radially inward along an outer surface of the hood rear wall and axially away from the rear wall to an annular fuel gas manifold box mounted close around the hood rear wall neck. The annular manifold box has a pair of axially spaced radial walls connected to rotate with the rotary hood and a nonrotating outer sleeve connected to a stationary fuel gas delivery conduit. An annular air manifold box, similar in construction to the fuel gas manifold box, is mounted close around the axially extending portions of the fuel tubes and between the fuel gas manifold box and the rear wall of the firing hood. Air conducting tubes mounted on the kiln shell also extend axially through the rotary hood and rear wall thereof and have portions which project radially inward and axially away from the rear wall to the annular air manifold box. The kiln is provided with a pair of radial discharge ports, circumferentially spaced 180* apart, for discharging processed material twice each revolution of the kiln. The air and fuel gas tubes are arranged along the kiln shell in two groups, with each group of tubes being on one side of the kiln and between the pair of kiln discharge ports to be spaced away from hot processed material discharged through the ports.

Apparatus for and method of controlling rotary kiln operation

Abstract: An apparatus for and method of controlling the operation of a cement kiln or the like in accordance with which means are provided for determining the temperature at two axially spaced locations within the calcining zone of the kiln, determining the differential between the temperatures measured at the two axially spaced locations as an indication of whether or not the burning zone of the kiln is located at a desired axial location within the kiln, and making proper control adjustment or adjustments to the kiln to maintain substantially constant the predetermined differential between the two measured temperatures, whereby to maintain the burning zone at the proper axial location within the kiln.

Production of iron, steel and ferrous alloys

Abstract: 1,213,641. Reducing iron ores. BRITISH IRON & STEEL RESEARCH ASSOCIATION. Jan. 4, 1968 [Jan.4, 1967], No.518/67. Heading C7D. Iron, steel or ferrous alloy is manufactured by, in a first stage, injecting a first hydrocarbon, e.g. through tuyeres 25 fed via line 1, and an O2 - containing gas, e.g. through lances 27 and tuyeres (26, Fig. 2) fed via line 3 into and/or over a molten iron bath 28, e.g. in a stationary, tilted or rotated converter or shaft kiln, to crack the first hydrocarbon to produce an H2-containing gas and reduce any iron oxides e.g. wustite to molten iron, passing the H2- containing gas, e.g. through a hollow trunnion 22 of the converter, in countercurrent to iron ore e.g. haematite in a second stage, e.g. in a shaft kiln, fluidized bed-containing vessel or rotary kiln 13 to reduce the ore at least partially, the reduced ore e.g. sponge iron/ wustite bed 10 being fed to the first stage, injecting a second hydrocarbon (the same or different from the first) e.g. from pipe 2 into the second stage to quench the H2 - containing gas stream passing therethrough so that incipient fusion of the ore is inhibited and its pore structure maintained, and tapping off molten iron 28 and slag 29 from the first stage. Effluent gas from the second stage drawn from offtake nipple 17 may be recycled to the first stage and burnt with the first hydrocarbon via line 6 to burner 5 and/or introduced into the second stage with the second hydrocarbon to provide the quenching stream, preferably after passing through a dust cyclone and water washer 14, and tubular heater 8, e.g. to heat the quenching stream to 225-725‹C. Either hydrocarbon may be gaseous, liquid or solid, or mixture thereof, e.g. methane, butane and/or naphtha. The carbon (smoke) simultaneously formed by the cracking dissolves in the molten bath to be burnt-off with the O2- containing gas injected. An electric furnace may be incorporated in the first stage to supplement the heat requirements. The ore, charged through feed hopper 15, may be initially beneficiated by magnetic separation, and comprise partially reduced ore and/or iron scrap, carbonaceous material such as coke or coal and/or a flux; the latter may be fed to the first stage into the molten iron, Specification 1, 187, 781 is referred to.

Cooler for rotary kiln

Abstract: A plurality of material cooling tubes are attached in parallel alignment around the periphery of the material discharge end of a rotary kiln. An oblique passage is provided from each tube to the interior of the kiln for conducting air from the tube to the kiln. A first duct is provided for receiving hot material from the kiln. The first duct is within the oblique passage and extends from the kiln a predetermined distance to a terminal portion thereof intermediate the kiln and tube. A second duct is provided which has a first end portion connected to the terminal portion of the first duct and the second duct projects out of the oblique passage to be exposed to surrounding atmosphere. The second duct has a second end portion connected to the tube. The second duct is a spiral that turns away from the adjacent end of at least about 180* to where it discharges material into the tube and the tube projects through the space inwardly of the spiral duct toward the adjacent discharge end of the kiln. The spiral duct, being exposed to atmosphere, is cooled and material therein is cooled, to reduce thermal stress in the assembly.

Control system of rotary kilns

Abstract: In a control system of a rotary kiln of the type comprising a power detector for measuring the driving power of the kiln and the output signal from the power detector is utilized to control the kiln, there is provided a synchronizing signal generator for generating one synchronizing signal during one revolution of the kiln, an integrator responsive to the synchronizing signal for integrating the output signal from the power detector for an interval corresponding to one revolution of the kiln, and a memory for storing the output signal from the integrator for use it for the control of the kiln.

Reduction of solid iron ore to hot metallic iron in a rotary kiln-flash heater-rotary reactor complex

Abstract: A METHOD IS DISCLOSED OF REDUCING SOLID IRON ORE PARTICLES TO HOT METALLIC IRON IN A CONTINUOUS SYSTEM INVOLVING A ROTARY KILN AND A FLASH HEATER AND A ROTARY REACTOR IN SERIES. IRON ORE PARTICLES, SUITABLE FLUXES FOR REMOVING IMPURITIES FROM IRON, AND SOLID FUEL PARTICLES ARE FED IN A CONTINUOUS STREAM OF SMALL VOLUME THROUGH THIS APPARATUS COMPLEX WITH THE OPEARATION SO CONTROLLED THAT THE IRON OXIDE IS REDUCED STEP BY STEP AS IT PASSES THROUGH THE SERIES OF APPARATUS ELEMENTS, WITH THE TEMPERATURE AND CHEMISTRY PROPERLY CONTROLLED AT EACH STEP SO THAT THE END PRODUCT DISCHARGED FROM THE ROTARY REACTOR IS MOLTEN IRON CARBURIZED TO ABOUT THREE OR FOUR PERCENT CARBON. THE INVENTION MAKES IT POSSIBLE TO UTLILIZE RELATIVELY INEXPENSIVE EQUIPMENT, OF MODEST DIMENSIONS, AND CAPABLE OF SIMPLE MAINTENENCE, WHILE PRODUCING A CAREFULLY CONTROLLED END PRODUCT.

Apparatus for reducing oxygen content of oxidic mineral ore

Abstract: A system with several variations is disclosed for reducing the oxygen content of mineral ore. The preferred embodiment of the system includes first, in mineral flow sequence, a preliminary traveling grate apparatus for drying and preheating agglomerates of finely divided mineral ore. Next, a rotary kiln is provided to further heat the agglomerates in a reducing atmosphere and preferably at least initiate the relatively more easily accomplished reducing steps which in the case of iron ore is the reduction of Fe203 or Fe304 to Fe0. After the kiln, a reactor apparatus preferably having a horizontal annular rotary grate is provided to perform additional steps, which in the case of iron ore is the more difficult reducing step of reducing Fe0 to Fe, form a network of metal bridges throughout the agglomerates to provide agglomerate strength and degradation resistance, and thereafter recover the heat for the process and cool the reduced mineral product. A gas flow system is provided to direct a gas stream generally counter to material flow with the gas stream being of reducing character as it passes through the reactor and at least a major portion of the length of the kiln. Near the gas discharge end of the kiln controlled amounts of air may be admitted to provide highly heated strongly oxidizing gases to dry and preheat the agglomerates on the preliminary grate and impart sufficient physical strength to the agglomerates so they can survive the tumbling action they will receive in the kiln. Strongly reducing gases are provided for the reactor by delivering methane or natural gas along with steam to a reformer, or by the partial combustion of hydrocarbon or carbonaceous fuels, for producing a gas stream rich in hydrogen or carbon monoxide and preferably both. After passing through a reducing portion of the reactor, the gas stream is passed through a condenser to remove the water formed by the reducing action of the hydrogen, and the gas stream is then divided into two separate branch streams with a first branch being directed to flow through the kiln. A second branch stream is directed through a carbon dioxide scrubbing system to scrub out CO2 formed by the reducing action of the CO; after which this gas stream is passed through a heat recovery and cooling portion of the reactor to recover heat for the process by heating the gas stream and cooling the reduced mineral product. The second branch gas stream which then has itself been heated by the agglomerate cooling operation, may be further heated, indirectly, by reformer flue gases, and thereafter have admixed with the second branch gas stream, fresh rich reducing gas from the reformer to provide a combined heated gas stream for passing through the reducing portion of the reactor. A layer of heat transfer media, such as steel balls, are provided to form a bed on the annular grate beneath the mineral ore agglomerates, to provide for the recovery of heat for the process by temporarily storing heat in the media while the gas stream is passed through a condenser and carbon dioxide scrubbing system, after which the gases again pass through the media on the annular grate to recover heat stored in the media and then recover additional heat for the process by cooling, to extent possible, the reduced mineral agglomerates.

Method for adjustment of the heat generating process in a rotary kiln with a heat exchanger etc.

Abstract: A rotary kiln system employing a pre-heater for feeding material to the kiln. A temperature sensing device is placed in the gas outlet of the rotary kiln and control means are provided to regulate the rate of feed of raw material to the pre-heater in response to variations in sensed temperature from a predetermined level.

Rotary kiln refractory lining

Abstract: Lining is carried out so as to produce a polygonal internal cross-sectional profile, for example, a hexagonal sectional. Successive ring courses can be offset.

Rotary kiln drier for particulate material

Abstract: The drier is provided with a number of sets of periphery spaced lifting vanes, the sets being spaced axially to provide annular gaps in which are disposed conveying vanes acting in opposite direction to the lifting vanes.

Heat treatment of material such as lime of varying - particle size

Abstract: In a preheating stage as well as a calcining stage in a rotary kiln whereby the larger size particles are heated in separate part streams of waste gases from the calcining stage, and at least the finer material with a particle size 0-5 mm is withdrawn as finished product after treatment in the pre-heating stage. The preheating stage for the fine material is carried out in a pneumatic heating system, e.g. a cylone, while the large particles are preheated in a grate furnace, or a shaft furnace. The fine material preheating is carried out after passing the material through a classifier, the voersize from which passes to the rotary kiln, and through which cooling air is passed and finally flows as combustion air to the rotary kiln.

Method and a rotary kiln for producing a bloated clay product

Abstract: A bloated granular clay product is manufactured by heating clay in a first step from atmospheric temperature to 300*-600* C. during a long period of time whereafter the clay now forming granules in a second step is heated to 1,150*-1,175* C. in a relatively short period of time i.e., about 15 - 30 minutes. The heating is effected in a rotary kiln having a drying section and a burning section. The first heating step is provided in the drying section and the second heating step takes place in a transition zone between the two sections. To ensure the quick heating in said second step there is provided heat transfer means in the transition zone.

Improvements in or relating to the treatment of iron ore fines

Abstract: 1,214,626. Reducing iron ores. INDIAN IRON & STEEL CO. Ltd. March 5, 1968 [Jan. 10, 1967], No.1400/67. Heading C7D. Sponge iron agglomerate for fading to a blast or other melting furnace is produced by feeding unagglomerated haematite iron ore fines "as received" at the ore treating plant directly to a rotary kiln and reducing with solid carbon e.g. coal, separating sponge iron from the product discharged, grinding and magnetically separating the fine ground sponge iron concentrate e.g. under wet conditions, and agglomerating e.g. pelletising and heat-hardening in the rotary kiln. Preferably reduction is effected at not-more than 1100‹C. in presence of limestone and/or dolomite flux. Unburnt coal recovered may be recycled.

Process for the reduction of lateritic ores

Abstract: 1282204 Reducing lateritic ores INTERNATIONAL NICKEL CO OF CANADA 31 March 1970 [28 March 1969] 15058/70 Heading C7D Lateritic ore containing one or more of Ni, Co and Cu as well as Fe e.g. limonite is selectively reduced in a rotary kiln by passing it countercurrent to reducing gases successively through a pre-heating zone, a strongly reducing zone in which the atmosphere is maintained at a ratio of reducing to oxidizing gases equivalent to a CO:CO 2 volume ratio of at least 1A5:1 by supplying reducing gases thereto through the kiln wall and supplying heat by burning fuel or part of the reducing gases therein, and a moderately reducing zone in which the atmosphere is generated to have a ratio of reducing to oxidizing gases equivalent to a CO:CO 2 volume ratio below 1.5:1 by partially burning fuel at the adjacent discharge end of the kiln, the latter also supplying up to half the total heat required in the kiln; combustion is controlled in both reducing zones to maintain the temperature throughout between 538 and 760‹C. The balance of the heat required may be provided by burning fuel introduced through the kiln wall. The fuel and reducing gases may be hydrocarbon oil and producer, water or other synthesis gases, or H 2 and CO. Up to 5% powdered coal, for supplying further fuel for combustion in the pre-heating zone, and up to 1% sulphide e.g. pyrites, to catalyse subsequent conversion of Ni to Ni carbonyl, may be mixed with the ore feed. A lateritic ore containing 38-46% Fe, 1-3% Ni and 0A05-0A3% Co, with MgO and SiO 2 , can be so reduced that all the Ni and Co, but e.g. less than 15% of the Fe content, are reduced to metal.

Adjusters for rotary-kilns drums

Abstract: The built in mechanisms in the rotary kiln, use for distributing and re-rolling the raw material charge in the drums. They have adjustable bearings, by which they can be located against the inner wall of the drum or the rotary cylinder of the kiln.

Device for protecting the collars of rotary kilns

Abstract: 1,235,368. Bearing rings for rotary kilns. SOC. DES FORGES ET ATELIERS DU CREUSOT. 25 Nov., 1968 [22 Dec., 1967], No. 55792/68. Heading F4B. In a rotary kiln, each bearing ring 2 of the casing 1 is internally protected by arcuate plates 7 which form a ring concentric with the bearing ring and spaced therefrom by spacers 5, 6, 11, and which are each fixed at only one end to permit circumferential expansion. The gaps between the spacers are left void or filled with refractory concrete 16. The plates 7 overlap one another and each includes a central slot at its fixed end to permit longitudinal expansion. The protective ring may be extended to protect other portions of the casing 1.

Aggregate for concrete

Abstract: 1,203,037. Porous concrete aggregates. ROTAG DEVELOPMENT CO. Ltd. 14 Nov., 1967 [29 Nov., 1966], No. 53412/66. Heading ClH. Concrete aggregates are obtained by mixing water with clay-free pulverized fuel ash, pelletizing and passing the pellets from the hot to the cool end of a rotary kiln to fire them. Steam formed from the water expands the pellets. Optionals are surfactants (amount given, but no examples), organic resin dispersion or sawdust which burn away leaving voids.

Manufacture of sodium or potassium tripolyphosphate

Abstract: 1324363 Sodium and potassium tripolyphosphates ALBRIGHT & WILSON Ltd 16 July 1970 [30 July 1969] 38159/69 Heading C1A An alkali metal tripolyphosphate is prepared by forming an aqueous solution of sodium or potassium orthophosphate having a concentration between 10 and 40% P 2 O 5 by weight and an atomic ratio of alkali metal to phosphorus such that it is capable of forming at least a substantial proportion of tripolyphosphate upon calcination; spray drying between 1/6 and 5/6 of this solution to form a dry mixture of orthophosphates; calcining the mixture in a rotary kiln at 200‹ to 600‹ C. until the orthophosphates have been converted to tripolyphosphate having a bulk density of from 0A4 to 0A5 specific gravity; cooling this tripolyphosphate and mixing it with the remainder of the aqueous solution of orthophosphates, the cooling being such that the mixture of tripolyphosphate with orthophosphate is at less than 120‹ C.; and heating the mixture in a rotary kiln at from 200‹ to 600‹ C. until the remainder of the orthophosphates has been converted to tripolyphosphate product.

Process of producing reduced iron ore pellets

Abstract: 1,204,637. Reduction of iron ore pellets. METALLGESELLSCHAFT A. G. April 1, 1969 [April 17, 1968], No.17093/69. Heading C7D. Reduced iron ore pellets containing 70-100% metallic iron are produced by pelletizing fine grained oxidic iron ore with 5-25% fine grained metallic iron (e.g. sponge iron or machining waste), which is added to the ore before or during the pelletizing, without the addition of carbonaceous material; firing the pellets at 700-1050‹ C. in a slightly oxidizing to slightly reducing atmosphere to give an average O/Fe mole ratio in the fired pellets of 1-1A4 and then directly reducing the pellets at 650-1250‹ C., but below the softening temperature of the charge, using solid and/or gaseous reductants. The pellets may include bentonite and may be dried before firing which may be carried out on a sintering machine or in a rotary hearth furnace (e.g. using the exhaust gases from the direct reduction). The reduction may be carried out with solid reductant in an electrically heated rotary kiln, or with gaseous reductant in a shaft furnace.