US3759730A - Process for utilizing coal residues - Google Patents

Process for utilizing coal residues Download PDF

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Publication number
US3759730A
US3759730A US00138873A US3759730DA US3759730A US 3759730 A US3759730 A US 3759730A US 00138873 A US00138873 A US 00138873A US 3759730D A US3759730D A US 3759730DA US 3759730 A US3759730 A US 3759730A
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cement
setting
binder
coal
ash
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US00138873A
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L Trief
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/24—Cements from oil shales, residues or waste other than slag
    • C04B7/28—Cements from oil shales, residues or waste other than slag from combustion residues, e.g. ashes or slags from waste incineration
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding

Definitions

  • the present invention relates to a process for utilising coal residues, particularly ash from .power stations and detritus from mining.
  • the object of the invention is to provide a process for utilising coal residues, in particular power station ash and detritus from mining, by transforming it in a simple and economic manner into a hydraulic binder capable of forming a real cement having the agglomeration properties of known cements, with at least equivalent hydraulic reactivity and initial and final setting properties, with a substantial resistance to decomposition after setting and with a structure similar to that of certain natural materials and providing an analogous hardness.
  • fine or pulverised crude ash is added to the pure hydraulic binder in a quantity dependent on the desired final properties of mechanical resistance of the mixed binder thus obtained.
  • the setting and hardening agent is a chemical base, preferably one characterised by the OH group, for example a strong base such as sodium hydroxide or potassium hydroxide. It can also be a chemical compound characterised by the 80;, group, for example calcium, potassium or sodium sulphate.
  • the setting agent has the elfect of developing at the time of hydration the setting and hardening properties of the hinder or, when used mixed with crude ash, of transforming the binder into a hydraulic binder whereof the ice physico-chemical cementing and pozzolanic characteristics are cumulative.
  • the step of transforming the fired mixture into a molten slag is followed by a purification step which comprises heating the said molten slag to a temperature of up to 1800 C. so as to efiect separation of the metallic elements, the less dense slag floating on the separated denser material.
  • a purification step which comprises heating the said molten slag to a temperature of up to 1800 C. so as to efiect separation of the metallic elements, the less dense slag floating on the separated denser material.
  • the slag is rapidly cooled and transformed into granules which are then comminuted (steps (0) and (d) above).
  • the invention further provides an apparatus for continuously performing the process of the invention.
  • This apparatus comprises:
  • the apparatus may also include means for further treatment of the hydraulic binder so produced.
  • FIG. 1 is a schematic view of an apparatus according to the invention
  • FIG. 2 is a schematic view in longitudinal section through a complex firing and melting furnace.
  • FIG. 3 is a diagram giving the average weight composition of a portland cement, an aluminous cement and a binder according to the invention.
  • FIG. 4 is a Rankin diagram showing the composition of two binders according to the invention.
  • An ignited furnace 41 is charged with a separately prepared mixture consisting of about 40% by Weight of power station ash containing no unburned products and about 60% by weight of limestone with a grain size below 5 mm.
  • This furnace comprises three separate but immediately successive sections. In the first section, 41a (FIG. 2), the charged materials are fired. This firing is performed at a temperature which varies according to the nature of the constituents of the mixture, but which should be below the temperature at which the materials begin to soften, this temperature being approximately 1300 C.
  • fuel oil or gaseous fuel may be used for firing the materials of the mixture coal.
  • the quantity of coal, where this is used, should be selected so that no unburned coal remains at the end of firing. Thus, with the above mixture, about 15% by weight of coal is used.
  • Section 41b is heated with a liquid or gaseous fuel or by electricity to a temperature of at least about 15 00 C.
  • a molten slag 57 is formed and flows continuously into a ladle 41c forming the third section of the furnace.
  • the temperature in the melting section 41b is raised to a maximum of about 1800 C.
  • separation of the dense metal elements is promoted.
  • the metal elements are deposited at the base of the tank 58 and the molten slag 57 floats thereupon.
  • the slag passes continuously into portion 41c, whilst the metal elements are dis-charged via a tap hole 410! and are collected in ingot moulds (not shown).
  • Metal elements are normally present in power station ash and mining waste products in quantities varying between 5 and 30% by weight, depending on the source of the coal used.
  • the metal elements recovered in ingot moulds could represent a valuable primary material for the metallurgical industry.
  • This separation step of the metal elements has the eifect of purifying and refining the slag, transforming it into a white binder having a commercial value much higher than that of conventional binders.
  • the temperature is lowered to about 1500" C., the liberated heat being recovered by any known means.
  • the molten slag leaving the ladle 41c flows continuously through a pipe 42 into which cold water is injected via a pipe 42a (FIG. 1), and the resulting molten granules fall into a drying drum 43.
  • a grinder 44 of known type where they are ground in a wet medium, obviating the necessity of any prior drying of the granules and permitting the production of a very finely ground product.
  • a grinding fineness corresponding to a specific area exceeding 5000 cm. g. measured by the Blaine method may thus be obtained.
  • a pure hydraulic binder is obtained from the grinder 44 in the form of a relatively soft paste which can have various uses.
  • the paste can be directly introduced by a pipe 46 into a tanker vehicle 4611 and delivered to the user.
  • the paste can be pumped continuously out of the grinder 44 to a mixing tank 45 with which is associated a second tank 47 containing ash in the crude state.
  • These two tanks discharge simultaneously onto two metering conveyers 45a and 47a leading to a mixer 51 which may discharge to various points, for example to a concrete mixer 54 for producing concrete, or to a storage silo 53 for placing in sacks, or to other points via a pipe 52.
  • the pasty binder leaving the grinder 44 can also be led directly to the concrete mixer 54 or silo 53.
  • the paste leaving the grinder 44 is led to a mechanical drier 49 where part of its water is removed, the partly dried paste then being supplied to the customer. It can also be led to a complete drier 50 which removes all the moisture, resulting in a fine powder which can be supplied directly to the customer. Alternatively, this powder can be fed to a mixer 55 where it is mixed with dry crude ash from the tank 48, the resulting mixture passing into a storage tank 56.
  • a hardening agent can be added to the pure hydraulic binder obtained by the above-described process.
  • the hardening agent may constitute a chemical base preferably one characterised by the OH group, for example a strong base such as sodium hydroxide or potassium hydroxide and is advantageously added in a quantity between 2 and of the weight of the binder.
  • Sodium carbonate can also be added.
  • the reagent may constitute a chemical compound characterised by the 80;; group e.g. sodium sulphate or calcium silicate, advantageously added in a quantity between 5 and of the weight of the binder.
  • the setting agent is added at the time of using the binder. If the pure hydraulic binder is transformed into dry powder the setting agent can be incorporated directly into this powder to form a complete binder similar to conventional binders.
  • a hydraulic binder obtained by the process of the invention permits a compression resistance of 250 kg./cm. to be obtained after 3 days and a minimum of 400 kg./ cm. after 28 days.
  • the tests were performed on mortar bars by the international RILEM method.
  • the binder has a reduced thermal reaction as compared with a pure portland cement, so that contraction is reduced after hydration. Furthermore, after final hardening the hydrated binder is characterised by a substantially total resistance to decomposition.
  • Binder A contained a total of 73% ash, 24% C210 and 3% NaOH.
  • the blast furnace cement tested contained 70% slag and 30% portland cement and the grinding fineness was 3700 cm. g.
  • Binder E contained a total of ash, 14% CaO and 3% NaOH.
  • binders from the waste products of coal mines.
  • the latter generally consist of heaps of excavated material from below ground, consisting mainly of silicoalumino-limestone materials, metallic materials and more or less adulterated coals.
  • the coal contained in the mining waste products is profitably used for firing other petrified materials forming the same.
  • the mining waste products i.e. the coal, metallic elements and the C210, Si and A1 0 constituents are analysed and it is thus possible to know whether the quantity of coal will suffice to fire the calcarous, silicous and aluminous materials contained therein.
  • any possible corrections which are necessary can be made for forming the melting and firing a furnace charge and applying the process of the invention.
  • a process for utilizing coal residues selected from the group consisting of power station ash and mining waste products comprising forming a mixture of said coal residues and calcium carbonate, firing this mixture at a temperature of about 1300 C., thereafter heating the fired mixture to a temperature of at least about 1500 C. to form a molten slag, quenching said slag with water to form wet granules, wet grinding said granules to obtain a hydraulic binder, and finally admixing a setting and hardening agent with said hydraulic binder.
  • a process according to claim 1 characterized in that said coal residues have a ferric oxide content greater than 4%, heating the molten slag to a temperature up to 1800 C. so as to separate iron from the molten slag, and reducing the temperature of the molten slag to about 1500" C. prior to said quenching.
  • a process according to claim 1 characterized in that crude ash is added to the hydraulic binder in a quantity to enhance mechanical resistance.
  • a process according to claim 1 characterized in that a mixture containing about calcium carbonate and about 40% coal residue is treated.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Processing Of Solid Wastes (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
US00138873A 1970-05-04 1971-04-30 Process for utilizing coal residues Expired - Lifetime US3759730A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
LU60850 1970-05-04

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US3759730A true US3759730A (en) 1973-09-18

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US (1) US3759730A (de)
FR (1) FR2090813A5 (de)
GB (1) GB1348061A (de)
LU (1) LU60850A1 (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4152169A (en) * 1976-11-04 1979-05-01 Tetronics Research And Development Co. Ltd. Production of hydraulic cements and cement-forming materials
US4174974A (en) * 1978-04-14 1979-11-20 Standard Oil Company (Indiana) Process for converting coal ash slag into portland cement
US4224077A (en) * 1978-05-10 1980-09-23 Olifer Vladimir P Raw mix for the production of portland cement clinker
US4242313A (en) * 1980-03-21 1980-12-30 Extraction Research & Development, Inc. Processes for the recovery of alumina from fly ash and production of cement constituents
US4295744A (en) * 1979-04-23 1981-10-20 Muskogee Environmental Conservation Co. Slurry gun
DE3408702A1 (de) * 1983-03-09 1984-09-13 Texas Industries, Inc., Dallas, Tex. Verfahren und vorrichtung zur coproduktion von zementartigen produkten
US4600438A (en) * 1983-03-09 1986-07-15 Texas Industries, Inc. Co-production of cementitious products
US20060032408A1 (en) * 2004-08-12 2006-02-16 Strabala William M Method of making pozzolands and cementitious materials from coal combustion by-products
JP2007514634A (ja) * 2003-12-18 2007-06-07 ラファルジュ 水硬性無機組成物、その製造方法、並びにそのような組成物を含有するセメント製品および水硬性バインダー
CN109550932A (zh) * 2017-09-27 2019-04-02 北京碳极极电科技有限公司 一种基于煤制油残渣的复合吸波材料制备方法

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4152169A (en) * 1976-11-04 1979-05-01 Tetronics Research And Development Co. Ltd. Production of hydraulic cements and cement-forming materials
US4174974A (en) * 1978-04-14 1979-11-20 Standard Oil Company (Indiana) Process for converting coal ash slag into portland cement
US4224077A (en) * 1978-05-10 1980-09-23 Olifer Vladimir P Raw mix for the production of portland cement clinker
US4295744A (en) * 1979-04-23 1981-10-20 Muskogee Environmental Conservation Co. Slurry gun
US4242313A (en) * 1980-03-21 1980-12-30 Extraction Research & Development, Inc. Processes for the recovery of alumina from fly ash and production of cement constituents
US4508573A (en) * 1981-12-02 1985-04-02 Texas Industries, Inc. Co-production of cementitious products
DE3408702A1 (de) * 1983-03-09 1984-09-13 Texas Industries, Inc., Dallas, Tex. Verfahren und vorrichtung zur coproduktion von zementartigen produkten
FR2542307A1 (fr) * 1983-03-09 1984-09-14 Texas Industries Inc Procede et ppareil pour la fabrication de produits cimentaires
US4600438A (en) * 1983-03-09 1986-07-15 Texas Industries, Inc. Co-production of cementitious products
JP2007514634A (ja) * 2003-12-18 2007-06-07 ラファルジュ 水硬性無機組成物、その製造方法、並びにそのような組成物を含有するセメント製品および水硬性バインダー
US20060032408A1 (en) * 2004-08-12 2006-02-16 Strabala William M Method of making pozzolands and cementitious materials from coal combustion by-products
CN109550932A (zh) * 2017-09-27 2019-04-02 北京碳极极电科技有限公司 一种基于煤制油残渣的复合吸波材料制备方法

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Publication number Publication date
DE2122027A1 (de) 1971-11-18
DE2122027B2 (de) 1976-03-11
LU60850A1 (de) 1972-03-09
GB1348061A (en) 1974-03-13
FR2090813A5 (de) 1972-01-14

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