Abstract: A method for removing contaminants from contaminated material such as contaminated soils and contaminated construction debris comprises the following steps: Separating the materials into a first fraction having particles of a size greater than 50 mm and a second fraction comprising remaining particles; breaking up the particles of the first fraction into particles of a size smaller than 50 mm; combining the particles of a size smaller than 50 mm and the second fraction to a combined fraction; drying the combined fraction at a temperature of between 100.degree. to 130.degree. C.; breaking up the combined fraction into particles of a size smaller than 2 mm; and subjecting the particles of a size smaller than 2 mm to a distillation process at a process temperature from between 300.degree. to 600.degree. C. Preferably, the distillation process is a vacuum distillation process with a process temperature of between 350.degree. to 450.degree. C.

Abstract: A method and apparatus for dewatering an aqueous coal slurry includes imparting high shear forces to the aqueous coal slurry in the presence of a peptizing agent to render coal particles hydrophobic by stripping clay from the coal particles and peptizing the clay in the aqueous medium of the slurry. The slurry is separating to recover coal particles and the aqueous medium is draining medium from the hydrophobic surface of the coal particles.

Abstract: Contaminated soils are treated in that an aqueous slurry of the soil is separated into a coarse fraction and a fine fraction, the fine fraction is subjected to flotation, the resulting froth is dewatered and then carried away as a pollutant concentrate, and the underflow from the flotation is dewatered and is then carried away as purified soil. An emulsified oily vegetable oil is used as a collector agent for the selective flotation or an emulsified light mineral oil is used as a collector agent for the selective flotation and a light mineral oil is stirred as a conditioning agent into the fine fraction before it is subjected to the selective flotation.

Abstract: A screening system incorporated into the system of sawdust collection for paper producing pulp. An upper and lower range of the sawdust particles is designated as between smaller, strength-inhibiting size particles and larger strength-enhancing size particles. A screen is provided to screen out the smaller size particles. The screen is made out of stainless steel to avoid rusting and corroding and also to more readily pass the moistened smaller size particles. The screen is sloped and agitated to induce shuffling of the sawdust mixture, the process of which results in a separation of about 50% of the particles as rejected smaller size particles and 50% as acceptable larger size particles desirable for paper producing pulp.

Abstract: A stream containing kerogen-rich and mineral-rich oil shale particles flow in a downward helical course such that the stream is confined in a manner to give the stream an outer and upper side having a first depth and comprising a substantial amount of said kerogen-rich particles, and an inner and lower side having a second depth and comprising a substantial amount of said mineral-rich particles, the first depth being greater than the second depth. The kerogen-rich and mineral-rich particles are subsequently separated in order to recover the kerogen-rich particles. The mineral-rich particles are further processed using froth flotation.

Abstract: A method and apparatus are disclosed for the microbubble flotation separation of very fine and coarse particles, especially coal and minerals, so as to produce high purity and high recovery efficiency. This is accomplished through the use of a flotation column, microbubbles, recycling of the flotation pulp, and countercurrent wash water to gently wash the froth. Also disclosed are unique processes and apparatus for generating microbubbles for flotation in a highly efficient and inexpensive manner using either a porous tube or in-line static generators.

Abstract: A process for separating bentonite and carbon carrier particles from an air-dust mixture generated from a mechanical used-sand reclamation unit and, more particularly, a process as aforesaid wherein the bentonite and carbon carrier particles are recycled to a foundry sand preparation unit.

Abstract: A process is disclosed for producing high brightness kaolin from ore containing silica, other types of clays, minerals such as ilmenite micas, feldspars and various metal silicates as well as organic matter. The process consists of sizing, a double floatation step, magnetic separation, leaching and oxidative brightening steps. This is a novel combination of conventional unit operations and in particular the use of a double floatation step to remove quartz and various trace minerals that interfere with achieving high optical brightness for kaolin.

Abstract: A method and an apparatus for removing impurities from plant fibrous material which constitutes residual products in the refining of tuber or root vegetables, fruits etc. The plant fibrous material is, for forming a first substance, adjusted to a TS content of at least approx. 25% whereafter the first substance is fractionated in a first screening device to form a first fraction. The TS content of the first fraction is reduced, for the formation of a first mass, whereafter the mass is dried, for the formation of a second substance. This is fractionated in a second screening device to form a second fraction which substantially exclusively consists of plant fibres.

Abstract: A method and apparatus for magnetically beneficiating a raw sample, such as coal or lunar soil is disclosed. The beneficiation is achieved using a novel of fractionating the sample into components of different magnetic susceptibilities. The results of the fractionation may be used to determine the type of magnet to be employed for large scale operations, as well as the appropriate fraction or fractions to be recovered for further processing.

Abstract: An aperature is formed in the bottom wall of the launder. A downwardly extending container communicates with the aperture. A weir is positioned immediately downstream of the aperture. The container and weir combine to form a separator. In the launder, free water and solids contaminants settle and form a bottom layer of dirty water. The layer is diverted into the container through the aperture and the weir temporarily retains a small head of it. Temporary retention in the separator therefore generates a vertical fluid column comprising an upper layer of relatively clean froth and a lower layer of dirty water, said layers having an ascertainable interface. The elevation of the interface is monitored and contaminated fluid is withdrawn from the container as underflow at a rate controlled to keep the interface elevation substantially constant. The froth overflowing the weir is reduced in water and solids relative to the original froth issuing from the flotation vessel.

Abstract: This invention relates to a method for recovering a bulk concentrate of zircon and a bulk concentrate of rutile-ilmenite from dry plant tailings. A process has been discovered for froth flotation by manipulating the surface charges of dry plant tailings. Conditioning reagents, sulfuric acid to lower the pH; corn starch to coat the minerals to be depressed; sodium fluoride to activate the minerals to be floated; and amine to float the activated minerals, are used in the flotation process.

Abstract: In the process for beneficiating a crude kaolin by the method which includes a wet classification step to provide a classified kaolin fraction having a PSD such that at least 50% by weight thereof are of less than 1/2.mu.m ESD and substantially 100% by weight are of less than 10 .mu.m ESD; and one or more steps wherein an aqueous slurry of the classified kaolin is at least partially dewatered by filtration; the improvement which comprises effecting at least one of said one or more filtration steps, by flowing said aqueous kaolin slurry through a ceramic filter plate which is characterized by a porous support layer and an overlying porous filtration layer, the ratio between the respective mean pore sizes of the filtration layer material and the base layer material being between about 2 and 50; the pore size in said filtration layer being in the range of from about 1 to 3 .mu.m, and the pore size in the base layer being in the range of from about 4 to 50 .mu.

Abstract: A method for reclaiming plastic and cellulosic fiber from plastic coated waste. The method includes the steps of introducing previously hydropulped plastic coated waste into a size reduction unit to reduce the plastic coated waste to a maximum dimension of about 1-4 inches. The plastic coated waste is then subject to flotation with agitation to separate the plastic from the cellulosic fiber. The cellulosic fiber is then screened, dried, and baled. The plastic is further reduced to a maximum dimension of about 1/2 inches and dewatered. The dewatered plastic is dried to a moisture content of less than 10% and rolled into plastic pellets. This method produces plastic pellets comprising from about 5 to about 10 weight percent cellulosic fiber and less than about 10 weight percent water from hydropulper plastic coating waste.

Abstract: Raw plums fed into a receiving tank and washer (1) are conveyed by a platform elevator (2) to a cord-type sizing device which enables their distribution toward two tray-carrying chains (5A and 5B). The trays are stacked on carts carried by platform elevators (8A and 8B). Once they have been filled, the carts can be transported to a cooking oven (9).

Abstract: An apparatus is disclosed for removing ash from repulped wastepaper which contains ash together with cellulosic fibers. The apparatus includes a frame and a plurality of rolls which are rotatably secured to the frame, such that the axes of rotation of the rolls are spaced and parallel to each other. The plurality of rolls include an upstream roll and a downstream roll having a cylindrical outer surface. A porous belt is supported by and extends around the plurality of rolls to define an endless loop. The belt moves between the upstream and downstream rolls for defining a screening portion. A headbox is disposed within the endless loop, and adjacent to the screening portion for ejecting the repulped wastepaper through the screening portion. A drainage device is disposed on the opposite side of the screening portion relative to the headbox for receiving ash passing through the screening portion.

Abstract: A method and apparatus for salvaging conductive material from electrical power transformers. In the method, the transformer core is removed from the transformer casing and cut so as to separate laminations from windings. The windings with conductive materials and insulative paper are cut into relatively short segments. These segments are then subjected to an aqueous caustic solution with sparging for separating the conductive material from paper insulation and lacquer coatings thereon. The solution is treated with a coagulating or flocculating agent in a separate vessel to remove dissolved cellulose, processed to separate oil and PCBs therefrom and then returned to treat additional windings. The method is adapted to continuous processing.

Abstract: A litter cleaning apparatus that has a large new litter receptacle, a waste receptacle and a cleaned and reclaimed litter receptacle. Brand new, or recycled, litter is introduced into the new litter receptacle and is opened at the bottom to release litter into a litter pan when necessary or when used litter is seen to be uncleanable. Used, soiled litter is taken from litter boxes and poured over a separator screen. Cleaned litter will fall through while waste can be dumped off the screen into the adjacent waste receptacle. The cleaned litter receptacle can be emptied from the bottom in order to fill litter pans individually or to empty the litter directly into a recycling bucket. The apparatus can be wheeled about from area or area on a large animal raising installation.

Abstract: A process for removing mineral matter from coal is disclosed. The process involves creating ultrafine coal by pulverizing the coal feed material and mixing it with an aqueous amine solution. The coal/amine solution is fed into a flotation cell and gaseous carbon dioxide is charged into the cell. The carbon dioxide reacts with the amine solution to form bubbles which carry the "clean" coal component of the coal feed material to the top of the cell for subsequent removal from the cell. The bubbles are reduced in size as they move up within the cell. The mineral matter, which is heavier than the clean coal, stays at the bottom of the cell and can be removed separately. The amine and the carbon dioxide used in the process can be recycled. An associated apparatus is also disclosed.

Abstract: A process for conditioning and compacting vegetable fodder prior to storage and shipment which comprises breaking standard-sized bales and adjusting the moisture level of the fodder to reduce pulverization during subsequent compacting and handling; while at the same time injecting mold inhibitors and nutritional additive before repackaging the fodder into more compact bales, cubes or pellets for shipment.

Abstract: The invention consists of forming an aqueous slurry of water and particles of ore carrying both metals and/or minerals which are passed at relatively high speed along an electrically isolated path in contact with electrically insulating materials and in the presence of air. This generates a positive electrostatic charge in the water droplets and enclosed particles and a negative charge in the electrically insulating materials through which they are being driven. The water droplets and hence the particles become differentially charged so that when they pass over an oppositely charged negative field, they are driven into the lower oppositely charged field body by the strong force of electrical attraction and the relatively weaker force of gravity. Should the negative collector contain an amalgamating material such as mercury and the ore, as an example contain gold, electrons are exchanged providing instant amalgamation of the surface of the gold.

Abstract: A process and apparatus for separating plastics from contaminants which includes a separation tank, a wash tank, a rinse tank, a lift conveyor, and a material dryer is disclosed. The separation tank is filled with a separation solution and includes a discharge auger for discharging material that sinks and a discharge chute for discharging materials that float. The separation tank may be rotated so that sink or float materials may be alternately deposited in the wash tank. The wash tank is filled with a wash solution and includes a discharge auger for discharging material from the wash tank into a rinse tank. The rinse tank is filled with a rinse solution and includes a discharge auger for discharging material to a lift conveyor. Both the wash and rinse tanks include adjustable front and rear legs, and a center support leg for adjusting the solution level in relation to their respective discharge augers for optimizing washing or rinsing of either float or sink materials.

Abstract: The present invention provides containers or storage bins for separate storage of the seeds of each size fraction in the course of their postharvest ripening, interposed between the primary and secondary seed cleaners and connected to the secondary cleaner through a conveyer, which effects a separate feed of the seeds of each size fraction for further treatment.

Abstract: A precious metal recovery system utilizing an amalgamation process which results in substantially complete recovery both of the precious metal sought and of the mercury utilized in the process. Mercury has undesirable health and environmental characteristics and the system of the invention assures its substantial containment. In the operation of the system, ore is classified and sorted out into a plurality of bins or holds containing ore having a substantially uniform particle size. The ore is then delivered, bin by bin, beginning with the smallest particle size, to apparatus which assures substantially complete amalgamation of all of the precious metal present in the ore. Thereafter, a resulting slurry of water and tails is first removed from the amalgamation apparatus and any residual mercury removed before its return to the environment.

Abstract: An improved apparatus and method for froth flotation of particulate matter is disclosed wherein ridges or ribs are provided on the froth discharge surface of the apparatus.

Abstract: The present invention relates to a method incorporating a sorter, cyclone and thickener for removing sludge from water, and includes the step of separating the inorganic constituents or matter in the sludge, such as stones, gravel, sand, etc., from the organic constituents or matter thereof, such as wood, roots, etc. The inventive method is also suitable for processing sediment that contains decaying organisms.

Abstract: A process for treating effluents contaiing cyanide from mining operations wherein magnetic separation is used prior to treatment with hydrogen peroxide.

Abstract: A defrothing apparatus whose inlet opening of the foamed liquid contained in a foam duct of a primary flotation apparatus is provided in the bottom of the foam duct. Starting from the lower area of the defrothing apparatus, a rotary flow (potential vortex) is generated in the apparatus by a recirculated lqiuid quantity from a secondary flotation apparatus. In the core of the rotary flow the gas quantity (air) is collected and removed through a removal pipe. Consequently, the foamed liquid from the foam duct of the primary flotation stage which is pumped to the secondary flotation stage contains small shares of gas relative to the total quantity of liquid, thereby allowing the pump to be optimally sized of efficiency and better control of the system.

Abstract: A flotation apparatus used in reclaiming resin materials from bottles and other scrap articles each comprising a first low density resin component (e.g., polyethylene) bonded to a second high density resin component (e.g., polyethylene terephthlate); the scrap articles are granulated and air classified to form a primary particulate scrap which is flotation separated in two successive stages. The flotation separation stages each include a first auger in an apertured-bottom trough positioned near the top of a flotation tank with inlet means depositing a flow of particulate scrap and flotation liquid into one end of the trough; the heavy material output is afforded by a second auger in the bottom of the tank, whereas the lightweight material outlet is an overflow weir at one side of the tank. A vigorous washing apparatus using a hot aqueous medium connects the first flotation stage to the second, and a feedback connection conveys low density scrap back from the second flotation stage to the first such stage.

Abstract: A process is described for recovering vanadium and zeolitic alumino-silicates from flyash and similar carbon-bearing heat treated materials. The process includes steps for the separation of carbon, followed by pressure leaching the carbon-depleted flyash in relatively dilute alkali metal hydroxide solutions at elevated temperatures. The leach liquor is separated from the residue and is subsequently treated in an amine containing solvent extraction process step for vanadium recovery, and optionally, for other metals present in the leach liquor. The vanadium in the strip liquor is precipitated to obtain vanadium containing compounds.The leach residue is treated separately to recover zeolitic alumino-silicates therefrom.

Abstract: A mobile seed cleaning and/or separating apparatus has a wheeled, self-propelled chassis mounting a plurality of cleaning and/or separating stations. The stations are interconnected by conveyors which transport the seed through the apparatus. The cleaning and/or separating stations include a coarse screen to remove material of a size larger than the seed to be separated, an aspirator to remove relatively light material, a pair of pocket cylinders to separate materials of different sizes and a screen cylinder to finally screen the seed. After cleaning, the seed passes through a weighing device which continuously batch-weights the seed and actuates a prickling machine to introduce a furyside, mold-inhibitor or other chemical.

Abstract: Froth or foam sulfur particle accumulation during the recovery of sulfur particles from a zone containing regenerated redox solution is reduced by agitating and removing the sulfur slurry in a plurality of streams, including at least one stream at a short distance from the top of the solution in the zone and at least one stream from the bottom of the zone and optionally recombining the streams after removal.

Abstract: A process for producing toner particles for developing electrostatic latent images, comprising the steps of introducing colored solid particles containing a binder resin into a multi-division classifying zone divided into at least three sections by partitioning means, so that the particles are fallen along curved lines; collecting a coarse powder consisting primarily of coarse particles in a first divided section, a medium powder consisting primarily of particles having a particle size within a defined range in a second divided section and a fine powder consisting primarily of particles having a particle size smaller than the defined range in a third divided section; feeding the classified coarse powder to a pulverizing step; and introducing the pulverized powder into the multi-division classifying zone. An apparatus for practicing the process is also disclosed.

Abstract: For the purpose of increasing the efficiency during drying of brown coals having a high water content and for the purpose of facilitating the purification of process waste water resulting in a drying process according to Fleissner it is proposed to spray hot water onto the raw coal and to separate the proportion in fine grain having a maximum grain size of 5 mm, preferably of 1 mm. In the following, the proportion in fine grain is subjected to an adsorption stage (5), noting that after a reaction time of at least 1 min, preferably of 2 to 5 min, a major portion of the soluble substances burdening the waste water becomes adsorbed on this fine grain. Subsequently, the waste water is further purified after a flocculating step in a flocculating reactor (6) and after a separating step (8) for separating solid matter, for which purpose can be used sand filters (10), adsorbing resins and activated carbon.

Abstract: A process for concentrating gold and/or uranium minerals by rendering the nonmagnetic minerals magnetic or weakly magnetic by causing a coating to form on the surfaces of the minerals. The gold and/or uranium are concentrated by use of a gravity-magnetic separator or a suitable high intensity magnetic separator.

Abstract: A method for the beneficiation of gallium from fly ash involves subjecting the ash to particle size classification while avoiding substantial rupturing of cenospheres and plerospheres in the ash and isolating thereby up to 30 percent of the finest ash particles which are lower in iron content.

Abstract: In an apparatus for processing moist dust and mud from dust removal equipment, especially in the steel industry, wherein the mud is concentrated, fractionated and dewatered in several steps the mud is dewatered in a centrifugal separator, to allow the mud from the dust removal equipment of blast furnaces and steel works to be dewatered in an environmentally acceptable and simple and cost effective way.

Abstract: The method of the present invention is a novel comprehensive process for maximizing the recovery of valuable mineral values from coal ash. Options may also be included for the production of saleable inorganic chemical by-products. The process employs both physical and chemical extraction techniques that maximize the yield of products while reducing the quantity of waste produced. Valuable minerals and chemicals such as cenospheres (hollow microspheres), carbon, magnetite (Fe.sub.3 O.sub.4), alumina (Al.sub.2 O.sub.3), iron oxide (Fe.sub.2 O.sub.3) and iron chloride (FeCl.sub.3) may be produced. Due to removal of carbon, magnetite, and iron oxide from the coal ash, the processed ash comprises a quality pozzolan.

Abstract: A method for removing fine-grained sediments from flowing or standing bodies of water. The sediment is dredged from the bottom of the body of water. The dredged sediment is dewatered and classified in a sieve plant. At least a fine-grained admixture material such as fly ash or refined clay is admixed to the dewatered sediment material. The admixture is granulated and the resulting granulate is dried and fired under swelling. The swelled, fired granulate is cooled and further processed. The light weight granulate is admixed to concrete or used in the production of building materials such as sinter blocks and bricks. The noxious materials and heavy metals contained in the sediment are substantially sealed into the granules produced by sintering. The resulting waste waters can be cleared such that they are suitable for feeding back into the bodies of water. The residues of the waste water treatment can also be employed as admixture component in the granulate production.

Abstract: A method is disclosed for improving the recovery of a conventional single or double stage flotation process for the benefication of phosphate ore. The method includes treating the discarded froth product of the conventional phosphate proces with waste slime from the flotation process. The slime and froth product is agitated to completely deactive the cationic reagent prior to the anionic treatment with new phosphate ore in a conventional flotation process.

Abstract: Particulate material such as sand is classified in two or more classifying devices (13 and 15) which operate on the principle of "hindered settling" each to provide a coarse underflow fraction and a fine overflow fraction. A chosen blend 12 of the underflow fractions is provided by pneumatic control circuitry (FIGS. 2,5,6) which actuates flow control valves (14 and 16) to open, by amounts in accordance with a chosen blend ratio, only when there is sufficient material available for blending.

Abstract: Finely-divided ore is beneficiated in a froth floation process carried out in a closed vessel containing a medium on which a froth is formed as a result of the injection into the bottom of the vessel of a gasified slurry which percolates upwardly and circulates in the medium. A lighter fraction of the ore froths on the surface of the medium and is conveyed hydraulically into a receiver wherein the gaseous component is separated from the froth and is recycled through a compressor for mixing with an ore slurry supplied to mixing nozzles which inject the slurry into the medium. A heavier fraction of the ore sinks into the medium and is collected by and exhausted from the vessel through an underflow siphon located between the surface of the medium and the mixing nozzles. A wet scrubber flows a series of fluid jets in a horizontal grid pattern underneath the surface of the medium for limiting the upward percolation of the heavier fraction to the surface.

Abstract: A process for removing residual mercury from scrap fluorescent lamp exhaust tubulation or similar scrap glass is disclosed. A very small predetermined amount of finely divided silica or alumina powder is added to the mercury contaminated scrap glass and the mixture is agitated for a very short predetermined time during which the mercury is stripped from the tubulation. The separated mercury, powder and glass mixture is then decanted through a screen of suitable mesh to remove the separated mercury and powder from the glass and the mercury is then rinsed with a suitable solvent to remove the oxide powder from the mercury.

Abstract: A method for separating carbon and iron bearing particles from zinc and lead bearing particles contained in an aqueous slurry of blast furnace dust and the recovery and reuse of the carbon and iron bearing particles as charge material in a blast furnace is described.An aqueous slurry of blast furnace flue dust is collected in a thickener. The thickened aqueous slurry is strained to remove large foreign matter and make a size separation at about 4 mm. The plus 4 mm particles are generally wasted. The aqueous slurry containing the minus 4 mm particles is fed into at least one hydrocyclone where a size separation is made at between about 3 and 5 microns. A substantial portion of the carbon and iron bearing particles report to the hydrocyclone underflow and a substantial portion of the zinc and lead bearing particles report to the hydrocyclone overflow. The carbon and iron bearing particles are passed to a preparation plant to be prepared for reuse in the blast furnace.

Abstract: A method for upgrading the bitumen content of tar sands, wherein a raw tar sand slurry admixture of tar sands, water, collectors, and dispersing/wetting agents is milled; conditioned and then separated by a series of froth flotations at ambient temperatures from about 2.degree. C. to about 25.degree. C. to recover a concentrated bitumen tar sand product which may be processed by conventional means to recover oil from the bitumen. Enhanced recovery of bitumen may be accomplished by moderate heating in one or more of the flotation zones to about 50.degree. C. The method permits recovery and recycle of various components used in processing of the tar sand.

Abstract: A control system of particulate material treatment plant comprising screening means which produces undersize and oversize fractions and which is controllable to vary one size fraction relatively to the other size fraction, preparation or dense medium washer means producing a relatively low ash oversize fraction and a relatively high ash oversize fraction and two storage bunkers for the undersize fraction and for the relatively low ash oversize fraction, respectively, the control system comprising sensor means for sensing the amounts of particulate material in each of the two storage bunkers and for deriving signals indicative of the sensed amounts, control means receive the derived signals and control the operation of the screening means in accordance with the received signals.

Abstract: A system for separating and classifying whole tree wood chip material comprising essentially wood and bark overs, chips and bark fines which is supplied to a large capacity surge bin. The chip material is augering in a forward direction in a monitored flow longitudinally away from the bin while passing it across a first stationary screen trough system having openings of a size to pass everything, while rejecting the overs. The acceptable chips and fines passed through the first screen trough system are then augered across a second stationary screen trough system having openings of a size to pass the fines while retaining the acceptable chips. Finally, the acceptable chips are moved forwardly toward a chip discharge location while the fines passed through the second screen trough system are separately collected.

Abstract: A method for classifying wet coal for obtaining coal charges suitable for use in a coke oven comprising classifying the wet coal directly in a cylindrical screen which rotates and revolves around an eccentric rotation shaft while blowing a high pressure gas stream to the screen to eliminate adhesion of the wet coal particles to the screen. The method enables a continuous and consistent classification of wet coals without the clogging of the screen and the dust pollution. The cokes obtained by dry distillation of the coal classified by the present method show high quality.

Abstract: The process of concentrating tin oxide minerals of fine particle size from material containing the same comprising the steps of forming an aqueous slurry of said material and subjecting said slurry to high intensity wet magnetic separation at a field strength and for a time sufficient to form a concentrate containing a major proportion of the tin oxide minerals originally present in the slurry.

Abstract: The disclosure concerns a process and an apparatus for recovering fiber suspension from a mixture of different types of waste paper. The waste paper is disintegrated in a pulper to form a fiber suspension comprised of individual fibers. After perhaps passing a presorting device, the fiber suspension passes through a sorting device which separates the fibers into a long-fiber fraction and a short-fiber fraction. The two fractions are subsequently treated in different ways, generally for the purpose of cleaning the fiber fractions. Various treatment techniques are disclosed, including separating impurities from the long-fiber fraction by flotation and/or bleaching the long-fiber fraction and washing the short-fiber fraction and/or treating it by flotation for de-inking the short-fiber fraction and perhaps thereafter sorting the short-fiber fraction to remove impurities.