Abstract: A granulating apparatus for continuously producing granules from powdery particles. The granulation chamber of the granulator comprises a feeder for supplying powdery particles to the granulation chamber and a spray nozzle for ejecting a binder solution on the powdery particles held in the granulation chamber. Powdery particles-drying hot gas is supplied from the bottom of the granulation chamber so as to vortically flow upward through the granulation chamber. The centrifugal force of the vortically flowing hot gas causes fully grown granules having a larger diameter to be distributed toward the peripheral wall of the granulation chamber. The granules fully grown to a prescribed diameter are selectively and continuously conveyed to a drying chamber through an outlet port formed in the peripheral wall of the granulation chamber. The granules thus brought are thoroughly dried in the drying chamber.

Abstract: In a rotation granulator, the injection nozzles for the powder are provided along the jacket surface of the granulator container over the rotary table, so that the powder will arrive directly in the range of the stronger flow. In order to prevent any interruptions of the operation due to the filter part, a two-chamber system is proposed in which the first and second chambers may be alternately cut off. This makes it possible to operate the installation without any interruption. In order to control the air supply, the rotary table is mounted so that it may be moved up and down, in order that the width of the air gap between the rotary table and the inner wall of the conical casing may be adjusted. Lastly, a device for taking of samples provides a system of sluices or channels by which the low-pressure space of the granulator is actively prevented from being in direct contact with the free atmosphere.

Abstract: The invention relates to a rotating drum having a lining which avoids caking-on, the rotating drum being lined with movable elastic material basic webs fitted at a distance from the inner side of the drum and the securing positions of the basic webs being covered over by preferably thinner elastic overlapping webs with bevelled edges.

Abstract: An apparatus for drying pellets of particulate material such as carbon black is characterized by a columnar drying vessel containing inclined trays or screens positioned so that the pellets or particulates roll from screen to screen down the column. Preferably, the pellets are subjected to countercurrent flow of drying gases while flowing down the screens. In other aspects, carbon black is pelleted with a nonaqueous liquid pelleting fluid and dried with vapors of the same pelleting fluid.

Abstract: A method and apparatus for granulation in which particulate feed material is charged into a rotary cylindrical vessel (12) having its axis disposed horizontally, and respective cover plate (16,18) at each end for retaining the feed material, and a treatment gas and a process liquid is passed into the vessel during rotation of the latter.

Abstract: Heat treatment of a material, e.g. a finely divided resin, wherein the material is introduced into a drum and agitated by rotating, spaced blades which whirl the material into a dispersion. The action of the blades heats the resin particles so that heat for the heat treatment is provided. The heat treatment can be, e.g. to cause small resin particles to coalesce with larger particles in the processing of polyethylene reactor flake, to improve flowability of the resin, or to admix resin and additive. To obtain increased capacity while the size of the apparatus is maintained within reasonable limits, two intersecting, generally cylindrical drums, each outfitted with an agitator, are used. Apparently the dispersions of the respective agitators slam into each other in the vicinity of the intersection causing additional heating.

Abstract: A method and apparatus for continuously generating sulphur seed nuclei inside the drum of a sulphur pelletizing system. The sulphur seed nuclei are generated in portions of the drum by elevating the temperature of the solid sulphur particles in the range of about 180.degree. to 230.degree. F. A portion of the sprayed liquid sulphur particles solidify into seed nuclei particles prior to contacting a falling curtain of solid sulphur particles in the area of the spray pattern having a minimum density of the liquid sulphur particles. The generation of seed nuclei may be confined to the feed end of the drum so as to leave the remaining portion of the drum available for product growth.

Abstract: A mixing apparatus particularly useful in carbon black pelleting has two parallel pinned shafts. The pins on each shaft are arranged in a double helix fashion with the pins interdigitating. The pins of each double helix are composed of two subsets of pins arranged in a single helix which single helices are, however, axially offset from each other. Thereby at any given axial location alternatingly opposite pin action is provided in the interdigitating zone, while surging of power is avoided.

Abstract: In a rotary drum spray grainer there is provided a deflector plate overlying the spraying nozzles in the spraying zone to provide a drying zone where spray grained particles fall in a substantially uninterrupted downward path through the drying gas.

Abstract: In a rotary drum spray grainer there are provided adjustable spraying nozzles in the spraying zone to achieve optimum spray pattern dispersion on the spray grained particles as the particles fall through the spraying zone.

Abstract: Scraper apparatus, preferably for pelletizers is disclosed, the scraper being adapted with a plurality of individual blades rotatable into contact with the walls of the pelletizer and removable after excessive wear.

Abstract: Apparatus for extracting precious metals from their ores in which the ore is particulated and mixed with a binding agent to form a paste. The paste material is discharged into a rotary drum at an extruding station where it is pelletized by forcing it through a perforated sidewall of the drum. The pellets are discharged onto a conveyor belt and are transported to a spray station where they are wetted with a lixiviant solution. The lixiviant coated pellets are then dried by exposure to a heated air stream at a drying station as they are transported to an open air curing stockpile. The cured pellets are heaped in a pile and are then washed with a water spray to yield a pregnant solution of a precious metal salt.

Abstract: A process and product of waste recovery at phosphorus furnaces is disclosed wherein small sized discrete particles of carbonaceous material or beneficiated phosphate ore are mixed with a mineral acid, an alkaline fluid and water, and the reacted mixture is tumbled in a horizontal cylinder at a temperature below that at which the carbonaceous material oxidizes to form agglomerates which are then indurated to discrete particulate size as desired for a charge component; the agglomerates are fed to a phosphorus smelting furnace together with other materials needed to make elemental phosphorus, furnace gases are cooled with recirculating water, a side stream of the water is taken off, treated, and used as feedstock in fluid fertilizers. Apparatus is disclosed for agglomerating coke and phosphate and, further, for measuring the abrasion and shatter resistance of agglomerates.

Abstract: Solid sulfur pellets are made by dropping sulfur particles in two distinct curtains of particles within a drum having a tumbling bed of such particles. The larger curtain of particles is sprayed with molten sulfur and the smaller is sprayed with water above the bed. This indirect application of water keeps the temperature of the bed as well as the other curtain of particles being sprayed with sulfur within predetermined temperature ranges which produce high quality sulfur pellets. Dust emissions are prevented by classifying as to size a third falling curtain of recycled particles and spraying molten sulfur on the side containing dust particles. Seed nuclei are produced by intermittantly raising the temperature of the tumbling particle bed about 40.degree. F. for short periods of time.

Abstract: An improved pelletizing apparatus comprising a pellet forming means having a slanted rotatable member, means for supplying particulate batch material to the pellet forming means, means for supplying liquid to the pellet forming means, means for rotating the rotatable member in a given direction, the pellet forming means being so arranged and constructed that the liquid and particulate batch material supplied to the pellet forming means combine to form pelletized batch material, wherein the improvement comprises paddle means for sensing the depth of material on the slanted rotatable member and transducer means connected to the paddle means and responsive to the depth sensed thereby for providing an output signal that is indicative of the depth sensed by the paddle means.

Abstract: A method of and apparatus for pelletizing a batch of particulate material comprising: supplying particulate batch material to a slanted rotatable surface; supplying liquid to the surface to render the particles with the ability to adhere to one another upon impaction; rotating the surface in a given direction to cause the particles and newly formed pellets to move up along the surface and then downwardly at least partially under the influence of gravity so as to move in generally elliptical paths, whereby individual particles are caused to impact against one another and adhere thereto to form pellets; sensing the depth of substantially finished pellets at a downward portion of an elliptical path; and changing the ratio of liquid to particulate batch material in response to a change in the depth that is sensed.

Abstract: An apparatus is provided for controlling the amount of dry particulate matter and liquid added to a rotary pelletizer. A transducer placed within the pelletizer senses a characteristic of the mixed material in the pelletizer. This characteristic may be, for example, the level of the batch or the size of the pellets produced. The transducer signal is then conditioned to provide a modified signal level corresponding to a desired characteristic level and which varies about that level corresponding, for example, to the variations of pellet size about its desired size. The modifier contains two stages which may be used independently with the other stage being used as a straight through one to one amplifier. The two stages may also be used cooperatively to provide an intermediate signal. The intermediate signal can be used to operate a display device and as the input to a second amplifier. The second amplifier then provides a conditioned signal input into a larger control system.

Abstract: A method of agglomerating materials such as lithium carbonate into pellets of a desired size utilizing water to achieve initial agglomeration of the particles comprising the materials. The initially formed pellets are subjected to drying to provide hard, easy-to-handle and package pellets, free of contaminating or unwanted binders such as starch.

Abstract: Solid sulfur pellets are made by dropping sulfur particles in two distinct curtains of particles within a drum having a tumbling bed of such particles. The larger curtain of particles is sprayed with molten sulfur and the smaller is sprayed with water above the bed. This indirect application of water keeps the temperature of the bed as well as the other curtain of particles being sprayed with sulfur within predetermined temperature ranges which produce high quality sulfur pellets. Dust emissions are prevented by classifying as to size a third falling curtain of recycled particles and spraying molten sulfur on the side containing dust particles. Seed nuclei are produced by intermittently raising the temperature of the tumbling particle bed about 40.degree. F. for short periods of time.

Abstract: The invention provides an agglomeration apparatus comprising an agglomeration chamber, a distributor for particles to be agglomerated feeding said chamber, means for projecting a stream of moistening fluid onto the particles and into the chamber, a fixed obstacle generally conical in shape positioned in the chamber in the path followed by the particles and in the axis of the stream of fluid and means for collecting and drying the agglomerates obtained.Preferably the obstacle is formed by a cone and a frustum placed one on top of the other, the angle at the apex of the cone being smaller than that of the frustum.

Abstract: A method and apparatus are provided for controlling the amount of dry particulate matter and liquid added to a rotary pelletizer. A transducer placed within the pelletizer senses a characteristic of the mixed material in the pelletizer. This characteristic may be, for example, the level of the batch or the size of the pellets. The transducer signal is then conditioned to provide a signal level corresponding to a desired characteristic level and which varies about that level corresponding for example to the variations of pellet size about a desired size. That signal is added to a second signal representing the actual liquid flow into the pelletizer or added to a second signal representing actual dry particulate flow into the pelletizer and modulates that respective flow to maintain the input of either the dry or the liquid material into the pelletizer as necessary. Additionally, a set point signal can be provided as a constant signal representing desired dry particulate in flow or liquid in flow.

Abstract: This invention, is an apparatus for grading pellets produced by a pelletizer from dry particulate batch material and a liquid, as for a melting furnace such as a glass furnace. The pellets are sensed by passing the pellets adjacent a graded passage. When a pellet reaches a graded passage matching its size, the pellet drops through the passage and at the same time actuates a sensor indicating a pellet of that respective size. The sensor is connected to a counting device which then can provide, through an appropriate control device, a count of over or undersized pellets or the pellet distribution. This information then can be appropriately used by the control device to control the amount of dry batch material or the amount of water introduced into the pelletizer and to maintain the pellets within a desired range.

Abstract: A carbon black pellet formed by the pelleting of flocculent carbon black. An outer portion of the pellet contains antioxidant to prevent oxidation of the pellet during drying. The antioxidant is contained in a shell having a thickness sufficient to prevent oxidation of the pellet instead of being distributed throughout the thickness of the pellet. The antioxidant can be admixed with additional carbon black and the admixture used to form the outer layer of a layered pellet or the antioxidant can be mixed with the pelleting liquid used to aid in pelleting the additional carbon black used to form an outer layer of a layered pellet.

Abstract: Multi-cell fluidization and atomization apparatus for the continuous production and/or coating of granules, for example in pharmaceutical and agricultural chemical industries, comprises a series of upright cylindrical cells through which the particulate material moves sequentially having inlet and outlet openings at various heights and rotary agitators therein. The material is fluidized in the cells and may also be contacted by an atomized liquid.

Abstract: An apparatus for the preparation of granules from fine powder in which a shaft is mounted for rotation about the longitudinal axis of a cylindrical housing, a screw conveyor blade is mounted on the shaft to convey powder entering the housing through an inlet to a plurality of stirring pins which are arranged in a double helix along the shaft in a granulation zone of the housing, a disc being attached to the shaft to partially close the cross-section of the housing in a mid-portion of the granulation zone.

Abstract: In a rotary pan pelletizer, a central circular portion of the bottom surface of the pan is raised above the level of the annular portion around this central portion, and a stationary central plough is disposed with its lower surface in close proximity to the raised central portion. Binder liquid is fed on to the raised central portion and in operation the central plough keeps the raised central portion substantially clear of build-up of the material to be pelletized, so reducing formation of lumps and stabilizing operation. Further ploughs or scrapers are disposed over the annular portion to maintain a constant level of build-up of material thereon, at substantially the same depth as the height of the raised central portion.

Abstract: Agglomerating apparatus in the form of a rotating drum and a method for agglomerating and controlling the size consist of carbonaceous material, such as particulate coal, finely divided char and, optionally, a binder such as pitch. Control of the agglomerate consist size distribution discharged from the drum is achieved by increasing the relative residence time of the small or growing agglomerates and by limiting contact between the large formed agglomerates and the small forming or growing agglomerates. The preferred means to insure adequate growth time for the small agglomerates consists of a plurality of annular ribs spaced about the inside wall of the drum and a cooperating scraping mechanism. The scraping mechanism comprises a plurality of scraper blades projecting radially from a rotating shaft throughout the length thereof of the agglomerate-forming section of the drum. However, at the annular paths wherein a rib is found the scraping blades are shorter in length.

Abstract: Apparatus is provided for handling heat-softenable batch material prior to melting it. The batch components are mixed together and then mixed with liquid and formed into balls or pellets of substantially uniform size and shape. The pellets are then collected into a heat-exchange chamber through which hot gases are passed from a melting unit in which the pellets are to be heated to a heat-softened state. The pellets thereby are preheated prior to entering the melting unit to save considerably on energy requirements. A physical characteristic and specifically the depth of a portion of the batch being formed into the pellets is sensed, the depth being related to moisture content. The ratio of the batch material and liquid is accordingly regulated to achieve uniformity in pellet size, which is influenced by the moisture content. Size uniformity is important in maintaining relatively free flow of the hot gases through the pellets in the heat-exchange chamber.

Abstract: Apparatus for pelletizing particulate materials in a pelletizing bed comprising, a drum having opened and closed ends and a cylindrical or conical wall therebetween. The wall is comprised of annular sections which are releasably secured together.

Abstract: A longitudinal oscillatory motion is imparted to a rotating shaft of a carbon black pelleter. The movement of the rotating shaft in longitudinal direction varies the paths of the outer ends of the pins radially mounted on the shaft and traveling near the inner wall of the pelleter chamber thus preventing a buildup of carbon black cake on said wall.

Abstract: A powder agglomerator and its method of use. The invention is used to take extremely fine flue dust particles in a collection bin and process them before sending the resultant agglomeration to storage or a further processing location. From its collection bin, the dust particles are discharged by gravity upon a lower rapidly rotating smooth horizontal disc. The bin discharge is offset slightly from the disc's center so that the particles are subjected to centrifugal force to move them to the disc's outer periphery. At the point where the particles are discharged on the disc, a liquid binder, like water, is sprayed on the particles to cause them to begin to agglomerate. After being sprayed, the wetted particles are agglomerated under the influence of centrifugal and tangential forces. When they reach the disc's raised edge, the particles are completely agglomerated at which time they fall over the edge into a discharge hopper located below.

Abstract: A pinned shaft and correspondingly a pinned shell are described having the pins attached to the cylindrical surfaces in such a manner that all of the pins are arranged in a geometrically symmetrical pattern of squares or equilateral triangles or equilateral hexagons with the further provision that the pins are not arranged along straight lines or on circles. By this arrangement of pins a very uniform action of the pins is achieved, the pin density being constant over the entire pinned shaft and the distance between adjacent pins being identical all over the pinned shell. A carbon black pelleting device incorporating such a pinned shaft.

Abstract: Particles being pelleted, e.g., flocculent carbon black being pelleted with water, are passed through alternating zones of increasing and decreasing pressure. An apparatus is disclosed in which a cylindrical shell comprises a rotatable shaft located substantially on the longitudinal axial center line of the shell. The shaft has pins positioned thereon forming at least one helix with alternate decreasing and increasing pitches along the helix thus to effect compression and expansion actions on the mass in the pelleter, thereby producing a narrow size range of pellets.

Abstract: A wet pelleting apparatus essentially comprises a cylindrical shell and a shaft having pelleting pins affixed thereto, usually in a helical arrangement. In cross-sectional area taken at right angles to the axis of the shaft which is substantially concentrically disposed within the shell, the annulus formed between the shaft and the configuration given to it and the shell inner wall and the configuration given to it decreases and increases as the plane of cross-section is moved from the feed end of the apparatus to the discharge end thereof. In one embodiment, the shaft has an undulating or repetitive hourglass configuration and the inner wall of the shell is rectilinear. In another, the inner wall of the shell can be given an undulating configuration. In a third, both the wall and shaft surfaces can be formed so as to cause, according to the invention, alternate compression and decompression of particles being pelleted.

Abstract: Washing and disintegrating means serve to wash and disintegrate the waste material and to continuously deliver the resulting washed and disintegrated material. A first conveyor serves to receive said washed and disintegrated material from said washing and disintegrating means and to remove water from said washing and disintegrating means and to remove water from said material. A dirt separator serves to receive said washed and disintegrated material from said first conveyor and to remove dirt from said washed and disintegrated material and to deliver the resulting cleaned material. A second conveyor serves to receive said cleaned material from said dirt separator and to remove water from said cleaned material. A water collector serves to receive water removed by said second conveyor. A return conduit serves to deliver water from said water collector to said dirt separator.

Abstract: A method and apparatus are disclosed for drying and pelletizing organic material such as animal waste, sewage and the like. The organic material is dried in two stages using a high temperature, rotating primary drying drum, and a lower temperature secondary louvred drying drum. The primary drum includes an inlet section and an outlet section. The inlet section includes a plurality of transverse chain curtains for increased heat transfer to the organic material, for breaking up the organic material and for cleaning the sides of the drum. The primary drum outlet section includes a plurality of vanes angularly attached to the inside of the drum to form an auger to retain the material in the drum until it is partially dried to a desired level. The organic material is then transported to the secondary louvred layer. The louvred dryer includes an input section, an output section and a central pelletizing section formed by adjacent portions of the input and output sections.

Abstract: A carbon black pelleter is dislosed in which pins are affixed to a rotatable shaft and extend radially outwardly from the shaft in a plurality of helical flights. The pins are arranged such that upon rotation of the shaft the trace of a pin of a first helical flight overlaps the trace of a pin of a second azimuthally adjacent helical flight to produce narrow pellet size range.

Abstract: Pellets having uniform size and excellent strength properties are manufactured without fluctuations in production from finely-divided moist material by rolling nuclei of substantially mutually identical size in at least one pellet-rolling circuit in the presence of the finely-divided moist material, to form pellets having at least one layer of said material surrounding respective nuclei.

Abstract: Apparatus for contacting fused solid materials with solid, liquid or gaseous materials, comprising a rotary drum, longitudinal baffles along the inner drum wall inside the apparatus, coaxial consoles being joined in a liquid- and gas-tight manner to faceplates of the drum, for lodging feeding and removing mechanisms. It is a major feature of the invention that a diverter baffle system is mounted from the consoles throughout the interior length of the drum. Two preferred embodiments are described: one for formulating plant protecting agents, wherein the baffle system includes a row of diverting baffles that can be pivoted inside the drum. The other preferred embodiment is suitable for extracting vegetable materials, and here the baffle system is constituted by a stationary drum having a slanting lapping formed therein, similarly pivotable diverting baffles being arranged along the lapping. Various additional and some optional structural features are disclosed for both apparatus embodiments.

Abstract: A briquetting plant for hot briquetting particulate matter, such as mill waste containing a material that softens when heated, such as iron oxide, which includes a low temperature tumbler type heat exchanger, an intermediate temperature tumbler type heat exchanger, a fluid bed furnace and a compactor, with the feed material being fed therethrough in succession. The briquettes produced by the compactor are first fed from the outlet of the compactor into the intermediate temperature heat exchanger, for liberation of heat therein, separated from the feed material by a screen at the outlet of the intermediate temperature heat exchanger and from such screen transported into the low temperature heat exchanger for further imparting of heat to the feed material. A second screen is provided at the outlet of the low temperature heat exchanger for separating and discharging the briquettes in relatively cooled form.

Abstract: In a mixing device adapted to mix materials flowing therethrough from an inlet end to an outlet end in which there are provided agitating elements as on a rotating shaft, there is provided an internal recycling means to impel at least a portion of the material flowing from the inlet end toward the outlet end countercurrently to the main flow, i.e. toward the inlet end to effect an in situ recycle. There is disclosed a pelleting apparatus having a horizontally-disposed substantially cyclindrical shell, a rotating, pin-equipped shaft, inlet and outlet means for feeding material to be pelleted and pelleting liquid into and through the device, the shaft having mounted thereon, at least over a length thereof, at least one reverse-flight or blade adapted to cause motion toward the inlet end of the device of at least a portion of the mass being pelleted.

Abstract: A strategically located series of spaced apart classifiers set at varying depths within a pelletizer pan operated to classify the forming pellets and also impart controlled energy into the forming pellets producing pellets of improved quality. Controlled classifying of the forming pellets stabilizes pellet output. With a stabilized pellet output obtained the need for driving the pellet pan with a variable speed device can be eliminated since pan rotation can be maintained at a constant speed.

Abstract: A longitudinal oscillatory motion is imparted to a rotating shaft of a carbon black pelleter. The movement of the rotating shaft in longitudinal direction varies the paths of the outer ends of the pins radially mounted on the shaft and traveling near the inner wall of the pelleter chamber thus preventing a buildup of carbon black cake on said wall.

Abstract: A process for forming balls from mineral ores, particularly iron ore, in which water is added to the ore and the balls are produced in a balling drum. The surface wetness of the balls so produced is determined by apparatus which measures the intensity of light reflected from the balls in a selected direction, and the output from the measuring apparatus is used to control the addition of water to the material fed to balling drum.

Abstract: Granular peroxybleach activated detergent compositions are disclosed containing a crystalline activator component having a well-defined particle diameter and a narrowly defined rate of hydrolysis. These compositions have improved stability, particularly with respect to the activator, under prolonged, particularly alkaline, storge conditions. Peroxybleach activator agglomerates having a specific particle diameter and detergent compositions containing these agglomerates are also disclosed. The agglomerating agent is defined through its inertness versus the activator and also in its melting point. The bleach-activator detergent compositions of this invention are stable under prolonged (alkaline) storage thereby remaining substantially unchanged with respect to the appearance and performance characteristics of the freshly prepared detergent composition.

Abstract: A carbon black pelleter is provided with a hollow pin shaft rotationally arranged in a housing. The shaft has openings connecting its hollow interior with the annular space between the shaft and the housing. The shaft is connected to a source of pelleting fluid.

Abstract: A first cylindrical drum member is rotatably supported on a platform assembly and has a longitudinal axis that is coplanarly aligned with the longitudinal axis of a second cylindrical drum member that is supported independently of the first drum member and positioned in tandem relation thereto. The first drum member has an inlet end portion through which a pair of feed screw conveyors extend to supply agglomerative materials, such as preheated coal and char, to the inner portion of the first drum member. An outlet portion of the first drum member extends into the inlet portion of the second drum member. A platform assembly is provided that includes a pair of vertically extending leg portions through which a pair of shafts transversely extend to permit pivoting the first drum member. The longitudinal axes of the respective drum members intersect at the transverse axis formed by the shafts so that the platform assembly is arranged to pivot about the intersection of the respective longitudinal axes.

Abstract: A carbon black pelleter comprising a pinned shaft rotatably arranged in a housing with the pin density being essentially constant over the entire shaft and with the further provision that not more than about 3% of the pins are located at the same axial location and that not more than about 10% of the pins are located at the same azimuthal location is provided for. The pins are arranged on at least one defective helix being defined by the fact that the location of the pins on the shaft is essentially that of a helically shaped line but that the pitch of axially adjacent pins, defined by the formulaP = 360.degree./a .multidot. twherein p is the pitch of axially adjacent pins, a is the asimuthal angular distance in degrees between axially adjacent pins along the defective helix and t is the axial distance between these axially adjacent pins, changes a plurality of times along the defective helix.

Abstract: An agglomerating unit having a rotatable, conical, downwardly, narrowing section on the interior surface of which moistened powder is deposited. Close to said interior surface a stationary scraper is mounted. When the conical section is rotated the powder is dislodged from said surface by the scraper. A very efficient removal of powder is obtained whereby the risk of biological or chemical deterioration of the powder is reduced.

Abstract: Apparatus is provided for handling heat-softenable batch material prior to melting it. The batch components are mixed together and then mixed with liquid and formed into balls or pellets of substantially uniform size and shape. The pellets are then collected into a heat-exchange chamber through which hot gases are passed from a melting unit in which the pellets are to be heated to a heat-softened state. The pellets thereby are preheated prior to entering the melting unit to save considerably on energy requirements. A physical characteristic and specifically the depth of a portion of the batch being formed into the pellets is sensed, the depth being related to moisture content. The ratio of the batch material and liquid is accordingly regulated to achieve uniformity in pellet size, which is influenced by the moisture content. Size uniformity is important in maintaining relatively free flow of the hot gases through the pellets in the heat-exchange chamber.