Abstract: A cogeneration process and system which provides for the reclamation of a grease fuel from a concentrated grease trap pumping waste stream and the use of said grease fuel in a compression ignition reciprocating engine for the production of electric power. The concentrated grease trap pumpings are heated and mixed in the first stage of the process to ensure all grease is liquefied. This warm mixed stream is then separated by centrifuge into a heavy stream consisting of water and sediments and an oil-rich stream consisting of oil, grease/water emulsion and residual water. This oil-rich mixture is heated sufficiently to evaporate the residual water as well as the water of emulsion yielding a water free grease fuel suitable for use in the compression ignition engine. Heat energy for grease liquefaction and emulsion breaking is supplied by an engine jacket water cooling circuit and an exhaust heat recovery, respectively.

Abstract: A method of storing and dispensing a fluid includes providing a vessel configured for selective dispensing of the fluid therefrom. The vessel contains an ionic liquid therein. The fluid is contacted with the ionic liquid for take-up of the fluid by the ionic liquid. There is substantially no chemical change in the ionic liquid and the fluid. The fluid is released from the ionic liquid and dispensed from the vessel.

Abstract: A method and apparatus are disclosed for removing fat floating on hot soup. A thermally conducting plate 14 having a flat underside is cooled to a temperature below that at which the flat solidifies and lowered onto the floating fat to cause the fat to congeal and adhere to its underside. The plate 14 is then raised to remove the adhering fat from the soup, and the fat adhering to the underside is scraped off by dragging the underside across a straight edge 22.

Abstract: The present invention relates to a kitchen utensil 10 for separating and removing congealed fat 30 from cooked food 12 in a cooking vessel 14. The utensil comprises: a generally planar portion 16 shaped to correspond with a shape of a receptacle 18 of said cooking vessel and sized to fit within said receptacle so that an outer periphery 20 of the planar portion is contiguous with an internal periphery 22 of the receptacle; and a handle to allow a user to handle the utensil. The planar portion 16 contains perforations 24 sized so that when the utensil is rested on food in said receptacle liquid fat generated during cooking is allowed to pass from the food through said perforations and when cool congealed fat is generally prevented from passage back through said perforations. The handle allows a user to remove the utensil and congealed fat from said receptacle.

Abstract: The present invention relates to a method of removing the fuel contained in the lubricating oil of an internal-combustion engine comprising an engine block (10) with an air intake circuit for a fuel mixture, a burnt gas exhaust circuit, an oil sump (44) and means (48) for pumping the oil contained in the sump. According to the invention, the method consists in removing, after pumping the oil, the fuel diluted in the oil.

Abstract: A bi-solvent cleaning system for cleaning precision components without the use of VOC solvents. The bi-solvent cleaning system provides for is a two mode operation for cleaning and rinsing precision components using VOC exempt solvents that is as effective as prior art VOC solvent based systems while subsequently allowing for recovery and reuse of a VOC exempt solvent.

Abstract: Methods and systems for processing organic waste material are provided. These methods and systems include integrating an anaerobic bio-digester and nutrient recovery module with a bio-production facility, which can locally provide feedstock for the bio-production facility, and can locally provide organic material for the anaerobic bio-digester. Methods and systems for integrating an anaerobic bio-digester with a gas cleaner are also provided, which can recover nutrients while cleaning the biogas produced by the anaerobic bio-digester.

Abstract: A method is provided for recovering oil from stillage including oil resulting from a process used for producing ethanol. In one embodiment, the method includes heating the stillage to a temperature sufficient to at least partially separate, or unbind, the oil therefrom. The method further includes recovering the oil from the stillage.

Abstract: Embodiments of the invention are directed toward a novel pressurized vapor cycle for distilling liquids. In some embodiments of the invention, a liquid purification system is revealed, including the elements of an input for receiving untreated liquid, a vaporizer coupled to the input for transforming the liquid to vapor, a head chamber for collecting the vapor, a vapor pump with an internal drive shaft and an eccentric rotor with a rotatable housing for compressing vapor, and a condenser in communication with the vapor pump for transforming the compressed vapor into a distilled product. Other embodiments of the invention are directed toward heat management, and other process enhancements for making the system especially efficient.

Abstract: The invention relates to a matrix liquid for producing machining suspensions, a machining suspension produced with the matrix and a method of fractionating the used machining suspension yielded after use. The invention also relates to a homogeneous mixture of a polymer or various polymers and water. The mixture can be used especially advantageously in all technical applications requiring a liquid with lubricating properties. In the present invention, a mixture of water and a thickening agent, respectively a polymer or a multiplicity of polymers, is utilized as the matrix liquid or lubricating liquid. The cutting grains can be separated very easily and quickly from the used machining suspension produced with this matrix liquid; for reuse. Less process water is required and the process water can be simply purified as there is no complicated getting rid of an alcohol charge.

Abstract: An evaporation based method for generation of high pressure steam from produced water in the heavy oil production industry. De-oiled produced water is processed through a high pH/high pressure evaporator driven by a commercial watertube boiler. The vapor produced by the evaporator is suitable for the steam assisted gravity drainage (SAGD) method being utilized by heavy oil recovery installations, without the use of once through steam generators that require extensive chemical treatment, and without requiring atmospheric distillation, which requires high power consuming compressors. Evaporator blowdown may be further treated in a crystallizing evaporator to provide a zero liquid discharge (ZLD) system and, with most produced waters, at least 98% of the incoming produced water stream can be recovered in the form of high pressure steam.

Abstract: The invention disclosed provides an apparatus and method for filtration and disinfection of ship's ballast water, such as sea water, based on hydrodynamic cavitation. The apparatus comprises a vortex diode with a tangential entry port and an axial outlet port with single or multiple bleeding holes. The disinfected water may be re-circulated through the system for additional disinfection or released from the tank into the surrounding waterways. The disinfection of seawater/ship's ballast water is achieved through filtration and hydrodynamic cavitation and the method does not involve use of any chemicals or any chemical reaction. The invented apparatus and method is simple, eco-friendly and can be fitted on to existing intake and discharge systems of any ship with minor modifications. It poses no risk to the health of the ship's crew unlike chemical methods and requires no special skill or additional manpower for its operation.

Abstract: The present invention is generally directed to new liquid-liquid extraction methods for the length-based separation of carbon nanotubes (CNTs) and other 1-dimensional nanostructures.

Abstract: Disclosed herein are processes for the recovery of 1,3-propanediol from an aqueous feed stream. The present invention involves contacting an aqueous feed stream that comprises water, 1,3-propanediol, and at least one contaminant with at least one solvent extractant to form a mixture. The mixture is separated into a first phase and a second phase. The second phase comprises a majority of the water from the aqueous feed stream. The first phase comprises solvent extractant and at least some of the 1,3-propanediol that was present in the aqueous feed stream. The weight ratio in the first phase of 1,3-propanediol to any one contaminant present is greater than the weight ratio of 1,3-propanediol to the same contaminant in the aqueous feed stream prior to the aqueous feed stream being contacted with the solvent extractant. The first phase can be removed from the separated second phase in order to recover the 1,3-propanediol.

Abstract: A method and system for recovering heat from a pretreated hot biomass stream is described. The method and system for heat recovery includes a flash cooler connected to a direct contact condenser. A liquid portion of the hot biomass stream flashes into vapors upon the hot biomass stream entering the flash cooler. The flashed vapors are transferred to the direct contact condenser. The flashed vapors and an incoming cold biomass stream subsequently come into contact with each other in the direct contact condenser, thereby causing heat to be transferred from the hot biomass stream to the cold biomass stream. As the heat transfer occurs, the flashed vapors condense onto the surface of the cold biomass.

Abstract: Apparatus, methods and systems for processing waste are provided. For example, a system for processing waste, wherein the waste comprises hard particulates embedded therein, can be provided. The system can comprise a waste disruptor, wherein the waste disrupter disrupts the waste and releases at least one of the embedded hard particulates from the disrupted waste; a segregator, wherein the segregator segregates at least one of the released hard particulates from the waste; and a dilution unit, wherein the dilution unit dilutes the waste. In some embodiments, the system can include a waste loader that provides waste continuously to the waste disrupter, which is configured to disrupt at least a portion of the continuously provided waste.

Abstract: A filtering apparatus having a vessel and a filter made from fluororesin and treated before filtering operation by at least one of adding thermal treatment in gas or liquid and penetrating with fluid composed of hot water or steam at a temperature of less than melting point of the fluororesin.

Abstract: Hot Water Sterilization of Activated Carbon beds or other adsorbents in filter tanks by including an electric or steam heating coil in the tank, alternately in the gravel underdrains, or in a plenum underdrain, or in an external canister.

Abstract: Apparatuses and methods for filtering particulates and volatiles from fluid systems. The apparatuses and methods include a particulate filter section, an evaporator section positioned adjacent the particulate filter section, and a manifold coupled to at least one of the particulate filter section and the evaporator section to direct flow through the apparatuses as desired.

Abstract: A process for purifying removal of crystals from their suspension in mother liquor by means of a washing column having forced transport in which the process chamber is encased by a metal wall which, on its side facing away from the process chamber, is heated at least along the length of the pure melt zone.

Abstract: A filter comprising a filter element with a filtering medium, mounted in a housing having a first end and a second end, and a passageway A removable generator to provide heated fluid for regenerating the filter element is to be connected to the housing adjacent the second end The second end of the filter element is constructed so as to permit a first portion of the heated fluid to flow toward the first end of the filter element, and the passageway is to allow a second portion of the heated fluid to flow from the second end to the first end, bypassing the filtering medium A flow director is positioned adjacent to the first end of the filter element for directing the second portion of the heated fluid discharged from the passageway toward the first end of the filter element.

Abstract: A method and a system for removing water from high water content solid such as high water content coal, which enables dewatering with small energy consumption. A liquefied material which is a gas at 25° C. under 1 atm. (hereinafter referred to as material D) is contacted with a solid containing water to allow the liquefied material D to dissolve the water contained in the solid, and to produce a liquefied material D having a high water content and simultaneously remove the water from the solid, and by vaporizing the material D in the liquefied material having a high water content, to thereby separate the water from the resulting gaseous material D, recovering the separated gaseous material D, and liquefying the recovered gaseous material by pressurizing, cooling or a combination thereof, to reuse the resulting liquefied material for removing water from a solid containing water.

Abstract: A device for recovering drinking water from condensate includes a self-supporting moulded part 11 formed of a transparent synthetic resin such as PET or PC, which is resistant to UV radiation. The moulded part 11 presents an open bottom area 16 with a collecting channel 15 on the edge side, with the collecting channel 15 presenting an inner wall 18 oriented towards the circumferential surface 12 and serving, at the same time, as floating aid, and with the moulded part 11 being provided with a pouring opening in its upper section 13 . For the manufacture of this device, a vacuum is created in a special deep-drawing tool not only in the region of the circumferential surface to be produced but also in the region of the collecting channel to be formed, and the moulded part is separated from a separated deep-drawing tool element outside the zone of the collecting channel.

Abstract: The present invention provides a method for treating water containing phenolic material such as bisphenol A, phenol, para tertiary butyl phenol, and 1,1,1-tris(hydroxyphenyl)ethane, as well as water soluble polycarbonate oligomers, and dispersed polycarbonate particles by extracting the phenolic material from the water using a water immiscible organic liquid containing an amine coupling catalyst. The treated water is then steam stripped to remove residual organic liquid and the amine. The organic liquid, containing the bisphenol A, phenol, para tertiary butyl phenol, and 1,1,1-tris(hydroxyphenyl)ethane, as well as water soluble polycarbonate oligomers and dissolved polycarbonate particles can be fed back to the coupling step of the polycarbonate process without further regeneration or treatment.

Abstract: A material contaminated with a solvent is treated with a hydrofluorocarbon to remove the contaminant. A preferred hydrofluorocarbon is tetrafluoroethane. Apparatus for carrying out the process is also described.

Abstract: An economical and environmentally responsible method of desalination and delivery of freshwater, concentrate, and electrical power to a site removed from the saline water source. Freshwater, concentrate, and power can be delivered by pipeline to multiple locations along the route and/or at the endpoint, thus distributing the beneficial aspects while minimizing the environmental impact of desalination facilities.

Abstract: The present invention discloses a comprehensive, efficient, and cost effective portable evaporator unit, method, and system for the treatment of brine. The evaporator unit, method, and system require a pretreatment process that removes heavy metals, crude oil, and other contaminates in preparation for the evaporator unit. The pretreatment and the evaporator unit, method, and system process metals and brine at the site where they are generated (the well site). Thus, saving significant money to producers who can avoid present and future increases in transportation costs.

Abstract: An apparatus, system, and method are disclosed for a filter for filtering a dosing fluid in an exhaust aftertreatment system. The filter may comprise a dosing tank configured to contain a dosing fluid, a filter media disposed within the dosing tank, and a support structure supporting the filter media to form a pathway for a flow of dosing fluid. Beneficially, the apparatus, system, and method of the present invention reduce the cost of operation and manufacture of the SCR system.

Abstract: A filtering apparatus for purifying cooking oil is provided. The filtering apparatus comprises a housing, a filter housing including a filter and a first conduit in communication with a deep fryer for extraction of cooking oil requiring purifying from the deep fryer. The apparatus further comprises a pump for pumping cooking oil through the first conduit, a valve assembly in flow communication with the pump, and a second conduit in flow communication with the pump which transports cooking oil to the filter housing. The filtering apparatus also comprises one or more heating cables attached to the first and second conduits and located adjacent the pump and valve assembly, and a thermostat in communication with a thermostat probe attached to the first and second conduits and the valve assembly and pump, whereby use of the thermostat prevents activation of said one or more heating cables when activation is not required.

Abstract: A method and system for providing Water for Injection using reverse osmosis. Water for Injection can be produced by reverse osmosis and the reverse osmosis membrane can be kept in a constantly self-sanitizing condition. One way of obtaining a constantly self-sanitizing condition is to maintain the reverse osmosis membrane at an elevated temperature during production of Water for Injection.

Abstract: Conversion of waste and other organic feedstock into sustainable energy, feed, fertilizer, and other useful products of reliable purities is accomplished using water, heat, and pressure. More specifically, the invention provides methods and apparatus that handle mixed streams of various feedstocks, e.g. agricultural waste, biological waste, municipal solid waste, municipal sewage sludge, and shredder residue, to yield gas, oil, specialty chemicals, and carbon solids that can be used as is or are further processed. Useful products can be diverted at various points of the process or internalized to enhance the efficiency of the system.

Abstract: A water distribution apparatus comprises a water user outlet facility and a water recirculation loop. The water re-circulation loop comprises a water supply, a water pump for establishing and maintaining a flow of water in the loop, a water delivery path extending from the pump to a water user outlet facility, a water return path extending from the water user outlet facility to the water supply, and a thermal disinfection apparatus disposed in the water delivery path for improving the potability of the water within the loop. A thermal heating apparatus and control is provided in the water delivery path or water storage tank to add thermal energy to prevent freezing of the stored water as well as the water flowing in the water re-circulation loop.

Abstract: A system and method for processing wastewater into usable water is provided. The method comprises: receiving a supply of wastewater; passing the wastewater into a refractory vessel having a heat generator associated therewith; increasing the temperature of the wastewater to a predetermined temperature using the heat generator for a predetermined amount of time to produce heated exhaust gases containing at least one product gas and water vapor; separating the at least one product gas and water vapor; and condensing the water vapor to produce usable water. The system comprises a refractory vessel defining a heat processing zone, a heat generator that is used to increase the temperature of the wastewater to produce a heated exhaust gas containing at least one product gas and water vapor, a scrubber to separate the product gases and the water vapor, and a condenser to condense the water vapor into usable water.

Abstract: Systems, methods and apparatus are provided for utilizing a substantially condensed phase cryogenic fluid for the purpose of remediation and retrieval of, e.g., spilled crude oil and other “oil spill”-related products from marine/aquatic and terrestrial environments. In some implementations, systems and apparatus are provided for applying a substantially condensed phase cryogenic fluid to a volume of spilled oil, and further having structure for collecting the spilled oil. Some implementations are environmentally-neutral. Substances other than oil may be remediated as well.

Abstract: Desalination apparatus based on porous restraint panels fabricated from a number of different layers of metal, thermoplastic, or other substances are used as sophisticated heat exchangers to control the growth of gas hydrate. The gas hydrate is produced after infusion of liquid hydrate-forming material into water to be treated, which liquid hydrate-forming material can also be used to carry out all the refrigeration necessary to cool seawater to near the point of hydrate formation and to cool the porous restraint panels. Hydrate forms on and dissociates through the porous restraints. The composite restraint panels can also be used in gaseous atmospheres where, for instance, it is desired to remove dissolved water.

Abstract: A process is disclosed that relates to the recovery of a metal catalyst from an oxidizer purge stream produced in the synthesis of carboxylic acid, typically terephthalic. More particularly, the process involves recovery of a metal catalyst from an oxidizer purge stream through the use of a pressure filter, the combining of water with a mother liquor to recover the metal catalyst and then subjecting an aqueous mixture so formed to a single stage extraction with an extraction solvent to produce an extract stream comprising organic impurities and a raffinate stream comprising the metal catalyst.

Abstract: The invention provides for the removal of impurities from treatment fluid including a base liquid and a variety of impurities contained in the base liquid by conveying the treatment fluid to at least one preheating separating device, including a preheating heat exchanger and a separator unit, before the admixture of a carrier gas to the treatment fluid. The treatment fluid is preheated by the preheating heat exchanger to a temperature below the boiling temperature of a base liquid so that the liquid impurities with lower boiling temperatures than the base liquid are evaporated and expelled thermally, whereby the evaporated and expelled impurities are separated in the separator unit of the preheating separator device. The treatment fluid is then evaporated and separated from impurities having a higher boiling point than the base liquid.

Abstract: Provided is a method for removing a liquid, in particular a supernatant, from a container with a sample, by creating an opening in a container with a sample consisting of solid constituents and a liquid, and subsequently centrifuging the container so as to cause the liquid to flow out of the container through the created opening. Also provided is a device for making a container suitable for use in the method.

Abstract: A method for removing low gravity solids from an oil-based drilling fluid includes directing the drilling fluid into a first inlet of a first line in fluid communication with a centrifuge, injecting steam into the drilling fluid through a second inlet in the first line, wherein the second inlet is upstream from the centrifuge, directing the commingled drilling fluid and steam into the centrifuge, rotating the centrifuge at a rotational speed sufficient to separate solids from liquids, collecting solids from a solids discharge, and collecting effluent from an effluent outlet, wherein the effluent has low gravity solids in an amount less than 1.5%.

Abstract: The invention relates to a device for thermally purifying waste water, comprising a tank through which waste water can flow. The inventive device is characterized by having at least one flow guiding means for guiding the waste water inside the tank in an essentially meandering manner, and by having at least one heating means inside the tank for regulating a predetermined temperature.

Abstract: A microfluidic device is provided for inducing the separation of constituent elements from a microfluidic sample by introducing phase changes in the microfluidic sample while contained in a microfluidic channel in the device. At least a portion of the microfluidic sample is frozen to cause fractional exclusion of the constituent element from the frozen portion of the microfluidic sample. Different portions of the microfluidic sample may be frozen in different sectors and at different times in order to cause movement in a desired direction of the separated constituent element. Portions of the microfluidic sample may be frozen in a sequential order of adjacent sectors within the microfluidic channel in order to cause sequential movement of the excluded constituent element toward one portion of the microfluidic channel. The frozen portion of the microfluidic sample is then thawed, wherein the separated constituent element remains substantially separated from the thawed, purified microfluidic sample.

Abstract: The present invention falls within the field of purifying oil-laden wastewater, which provides a method for purifying coke-cooling wastewater in a delayed coking process in petroleum chemical field. The method comprises the following steps: (a) cooling the coke-cooling wastewater produced in a delayed coking process to 5-55° C. under 0.1-0.25 MPa absolute pressure, to obtain cooled coke-cooling wastewater; (b) subjecting the cooled coke-cooling wastewater to solid-liquid separation, to obtain a coke breeze phase and a liquid phase; (c) further separating the obtained liquid phase, to obtain an oil phase and a water phase; and (d) further discharging water from the obtained oil phase, to obtain the separated oil phase. The present invention also provides an equipment for carrying out the method.

Abstract: A method and apparatus for removing solid particles from a three-phase stream that utilizes a separation vessel comprising a vapor-liquid separation zone and an overlying vapor-solid separation zone. The vapor-solid separation zone can comprise a solids flow inhibiting structure operable to remove at least a portion of the solid particles in the vapor stream. In one embodiment, the solids flow inhibiting structure comprises at least one packed section and/or at least one spray nozzle operable to wet at least a portion of the packing. In another embodiment, the cross-sectional flow area of the vapor-solid separation zone can be smaller than the cross-sectional flow area of the vapor-liquid separation zone.

Abstract: An engine oil filter assembly and method for removing solid and liquid contaminants from engine oil. After solid contaminants are removed by passing the oil under engine pressure upwardly through a fibrous filter element within a lower portion of a canister, the oil is then forced through a separator after which the filtered oil under pressure decompresses. A lid having a downwardly sloping central portion is closely spaced above a similar sloping central portion of the separator to define a heating channel therebetween. A heating element in fluid isolation from the heating channel radiates heat through the central lid portion to vaporize liquid contaminants still in the oil, the vaporized contaminants discharging through a vapor vent in the lid, the decontaminated oil passing by gravity through the heating channel into a drain insert and back into the engine via an oil return port.

Abstract: An apparatus and method for separating the output fluids of a well by way of efficiently applying heat to the fluids. Separation takes place in a sealed vessel to which heat is applied to the fluid by contact with a multi-pass firetube assembly through which hot exhaust gas is expelled from a forced draft burner. The firetubes forming the assembly are of smaller diameter than used in conventional separators and not subject to high leakage experienced in conventional separating vessels, and the heat transfer is highly efficient resulting in less fuel consumption and less emission of greenhouse gases.

Abstract: Energy is stored and transferred by separating a sodium sulfate product from water containing sodium sulfate, adjusting the phase change temperature of the sodium sulfate product, storing energy in said product by heating the product above the sodium sulfate-sodium sulfate decahydrate phase change temperature and transferring the stored heat by cooling the heated sodium sulfate product to below said phase change temperature.

Abstract: The present disclosure is directed to a method of improving the transfer of slurry in a Bayer process through the addition of one or more chemical species to a Bayer process, wherein said chemical species is selected from the group consisting of: non-ionic surfactants, polyglycols, polyglycol ethers, anionic surfactants, anionic polymers, and a combination thereof. The present invention is also directed to a method of deaerating a slurry in a Bayer process through the addition of an effective amount of one or more chemical species to a Bayer process, wherein said chemical species is selected from the group consisting of: non-ionic surfactants, polyglycols, polyglycol ethers, anionic surfactants, anionic polymers, and a combination thereof.

Abstract: Improved oil reconditioning systems and methods are disclosed. One preferred system provides an oil purifier for an internal combustion engine for separating contaminants in an oil stream from the oil. The system may include a housing, an oil distributor, and a heating element. The housing may enclose a platen having an evaporation surface. The oil distributor may also be located in the housing and may be configured to receive an incoming oil stream. The oil distributor may have a discharge manifold for transforming the oil stream into a mist. The mist may be directed toward, and distributed over, at least a portion of the evaporation surface. The heating element may be in thermal communication with the platen. The evaporation surface may be heated to a temperature sufficient to volatilize the contaminants, resulting in a purified liquid oil which may be collected and reused with the engine.

Abstract: The invention relates to an apparatus for the transfer of organic compounds from a first liquid phase to a gaseous phase and from said gaseous phase to a second liquid phase, comprising a packed stripping column (2), a housing (5), a shell (1), a means for introducing the gaseous phase at the bottom end of said packed stripping column (2), a distributor (4) for distributing said first liquid phase onto said packed stripping column (2), causing said first liquid phase to trickle down said packed stripping column (2) counter-currently to the flow of the gas phase and causing the gas stream leaving said packed stripping column (2) at its top end to have a higher content of organic compounds than the gaseous phase introduced at the bottom end of said packed stripping column (2), one or more ducts (9/26) allowing the gaseous phase leaving said packed stripping column (2) to flow downwards to the bottom end of a packed scrubber (3) enclosed in a housing (25), a distributor (12) on top of said packed scrubber (3) ca

Abstract: Alkaline waste waters formed in the washing of crude nitrobenzene which has been prepared by the adiabatic nitration of benzene with nitrating acid, washed in an acidic washing process, and then washed in an alkaline washing process are treated. The alkaline waste water being treated generally contains benzene in a concentration of from about 100 to about 3000 ppm and nitrobenzene in a concentration of from about 1000 to about 10,000 ppm. In the process of the present invention, undissolved benzene and/or nitrobenzene are separated from the alkaline waste water, residual benzene and/or nitrobenzene is/are then optionally stripped out of the alkaline waste water, and the alkaline waste water from which benzene and/or nitrobenzene has been removed is heated to a temperature of from 150 to 500° C. under excess pressure with the exclusion of oxygen.