WO1995011197A1 - Floculants - Google Patents

Floculants Download PDF

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Publication number
WO1995011197A1
WO1995011197A1 PCT/GB1994/002181 GB9402181W WO9511197A1 WO 1995011197 A1 WO1995011197 A1 WO 1995011197A1 GB 9402181 W GB9402181 W GB 9402181W WO 9511197 A1 WO9511197 A1 WO 9511197A1
Authority
WO
WIPO (PCT)
Prior art keywords
iron
aluminium
liquor
solution
halide
Prior art date
Application number
PCT/GB1994/002181
Other languages
English (en)
Inventor
Neil Clarke
John Harris Newton
Original Assignee
Laporte Industries Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Laporte Industries Limited filed Critical Laporte Industries Limited
Priority to AU77899/94A priority Critical patent/AU7789994A/en
Publication of WO1995011197A1 publication Critical patent/WO1995011197A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G49/00—Compounds of iron
    • C01G49/009—Compounds containing, besides iron, two or more other elements, with the exception of oxygen or hydrogen
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/48—Halides, with or without other cations besides aluminium
    • C01F7/56—Chlorides
    • C01F7/57—Basic aluminium chlorides, e.g. polyaluminium chlorides
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/84—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by UV- or VIS- data
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
    • C01P2006/66—Hue (H*)

Definitions

  • This invention relates to flocculants, to a process for manufacturing them from waste acidic liquors and to a process for the treatment of water, aqueous effluents, such as sewage effluents, or other aqueous liquids using the flocculants.
  • Such a treatment may be applied to the production of potable water, to the treatment of industrial effluents, for example to reduce the content of metallic contaminants in such effluents, to the treatment of sewage effluents, for example to reduce the content of organic matter or to the treatment of other aqueous liquids requiring purification.
  • the present invention relates to the production of a flocculant which may give an acceptable performance at pH levels outside the range referred to above and which may be produced from liquors which are currently processed at considerable expense to render them suitable for waste disposal.
  • the present invention provides a process for the production of a flocculant from an acidic aqueous liquor containing dissolved salts of aluminium and/or iron, comprising contacting the liquor with a basic material capable of reacting with the dissolved aluminium and/or iron salts to precipitate aluminium and/or iron values, separating the precipitate in the form of a cake or slurry from the remaining liquor, treating the cake or slurry with hydrochloric acid to redissolve aluminium and/or iron values and separating suspended solid matter from the resulting solution.
  • the solution contains ferrous iron the solution is preferably treated with an oxidising agent to convert iron to the ferric form as hereafter indicated.
  • the flocculant product of the invention may be a "poly (aluminium and/or iron) halide" which term is used to encompass the alternatives that iron and aluminium are present as a single polymeric species or at separate polymeric species as well as the alternative that either iron or aluminium is absent.
  • the iron content the product of the invention is anticipated to provide a dense floe blanket and has shown excellent storage stability.
  • liquor is used herein in a practical sense to refer to liquid plant effluent and includes any suspended solid matter with may be present in the effluent. Waste acidic liquors containing dissolved aluminium and/or iron compounds and which are suitable for use according to the present invention are produced on a large scale in various industries.
  • aluminosiliceous or aluminoferrosiliceous minerals such as smectites, kaolinites, attapulgites, sepiolites or the like and particularly, within the smectites, the montmorillonites, with acids such as, for example, sulphuric acid or hydrochloric acid, to increase the surface area of the minerals and to activate them for various uses, for example for edible oil purification or for paper coating applications, is practised on a large scale.
  • the acidic liquor so produced contains a substantial proportion of dissolved aluminium and/or iron compounds. This liquor may be neutralised with lime to produce a cake or slurry which is usually disposed to land ⁇ fill.
  • Acidic mine drainage liquor may contain a substantial proportion, for example up to about 1000 mg/1 of dissolved iron compounds calculated as Fe and up to about 4000 mg/1 of sulphate. Such liquor may likewise be neutralised with lime to produce a slurry which may be aerated to convert the iron to the ferric form and then allowed to settle to produce a solid waste product for disposal. Waste pickling liquors contain substantial quantities of dissolved iron compounds. The disposal of such waste products represents a considerable expense and is increasingly considered to be undesirable ecologically and it is of considerable benefit to industry, and environmentally, to provide means for utilising them as a raw material.
  • the montmorillonite clay minerals which term is used to include bentonites, are layered minerals composed of an octahedrally coordinated aluminium layer connected by the sharing of oxygen atoms to two adjacent tetrahedrally coordinated silicon layers.
  • the aluminium in the octahedral layer is partially substituted by iron and may also be substituted by magnesium or other atoms and the silicon in the tetrahedral layer may be partially substituted by aluminium.
  • Such minerals have appreciable surface area which is increased by acid treatment for a variety of applications. The effect of acid treatment is to dissolve aluminium and iron preferentially from the octahedral layer.
  • the liquor resulting from the acid treatment contains dissolved aluminium and iron sulphates.
  • the treating acid may alternatively be hydrochloric or other mineral acid or a suitable organic acid and the composition of the resulting liquor will differ correspondingly.
  • a typical acidic liquor may contain from 0.5% to 4% for example 1.5% of aluminium compounds calculated as AI2O3, 0.2% to 3% for example 0.8% of iron compounds calculated as F ⁇ 2 ⁇ 3 and may have a free acidity of 0.5% to 2% for example 1%.
  • an acidic liquor produced as described above may be contacted with sufficient of the basic material, and preferably with an excess of up to 100% thereof, to precipitate aluminium and iron values, usually as the hydroxides or hydrous oxides.
  • the basic material preferably is or comprises one or more magnesium compounds, such as magnesium carbonate, suitably as magnesite, magnesium hydroxide or other suitable magnesium compounds.
  • the majority of the sulphate anions remain in solution in the form of magnesium sulphate.
  • the precipitation may be conducted at ambient temperature or at the temperature of the acidic liquor which may, for example, be from 10°C to 50°C.
  • a typical composition for the filter-cake so produced from the sulphuric acid treatment of a montmorillonite mineral may be:
  • Some of the above constituents may be absent.
  • the silica may be absent if the acidic liquor is not derived from the treatment of a siliceous mineral.
  • the iron may be present substantially in the ferrous form unless such has been oxidised to the ferric form by an addition of an oxidising agent at some preceding point in the history of the liquor.
  • the magnesium content of this product may itself be in polymeric form.
  • This product may be used to reduce the phosphate content of a water by precipitation as magnesium phosphate.
  • the cake or slurry is digested by treatment with hydrochloric acid in, for example, a 1:1 to 2:1 cake:acid weight ratio.
  • the digestion may be conducted at a somewhat elevated temperature, for example at 40°C to 90°C, for, for example for 10 minutes to 2 hours.
  • the pH of the digestion liquor should be at least 2 preferably at least 2.5 and, for example, up to 4.
  • metallic aluminium and/or iron may be introduced either during the digestion of the filter cake or slurry or to the digestion product. It has been found that while a basic poly(aluminium and/or iron) chloride product may be produced directly from the digested cake this has a relatively low charge density and could not be expected to be of particularly high effectiveness as a flocculant. The inclusion of a relatively small quantity of metallic aluminium or iron considerably improves the product and results in a product having a charge density in the range of about 400 to 700, or to 900, meq/g. The improvement in the product appears to be greater than would be expected having regard to the quantity of metallic aluminium and/or iron added.
  • the aluminium and/or iron used in the present process may be in the form of powder, pellets, swarf or the like. Very suitably the aluminium may be in the form of shot and the iron in the form of powder.
  • the dissolution in the hydrochloric acid digestion liquor is preferably assisted by elevated temperature. The use of pressure and the higher temperatures normally associated with this is not necessary and a temperature slightly below reflux temperature, eg up to 20°C below reflux temperature, will suffice. The use of reflux temperature is not excluded but it may be preferred to avoid it for practical operational reasons. It is found that the dissolution of the aluminium metal proceeds relatively rapidly for example in from about 15 minutes to 2 hours although if iron metal is present this duration may have to be extended.
  • the quantities of aluminium and/or iron are preferably controlled to achieve the desired degree of improvement in the final product and may be from 10% to 100% by weight based on the aluminium/iron content of the digestion liquor.
  • suitable control of the hydrochloric acid digestion/metal dissolution process can enable the separation of iron from the liquor to produce a basic polyaluminium halide product or a basic poly(alumunium/iron) halide product containing a decreased proportion of iron. If the hydrochloric acid digestion liquor produced as described above is aged for at least 0.25 hours, for example for from 0.5 to 24 hours at a temperature of for example ambient temperature to 60°C before the addition of aluminium metal the dissolution of that metal is accompanied by the precipitation or crystallisation of iron in the metallic form. This metallic iron may readily be separated from the product.
  • a process for the treatment of mixed aluminium halide/iron halide solutions to separate iron therefrom comprising ageing the solution, adding aluminium metal to the aged solution, allowing metallic iron to precipitate or crystallise and separating the remaining aluminium halide from the metallic iron.
  • the aluminium halide/iron halide solution preferably has some or all of the features of the hydrochloric acid digestion liquor described above.
  • the poly(aluminium and/or iron)halide product solution also contains silicon in tl ⁇ s dissolved form. It may be present, typically, in at leas ⁇ 0.02 mg/kg, more generally in at least 0.05 mg/kg and, for example, up to 0.5 mg/kg or more, calculated as Si and based on the weight of the solution. Soluble silicon may help to reduce the biological effect of aluminium in water and may therefore be advantageous in a water treatment product.
  • the liquor containing the mixed aluminium/iron product is preferably treated to achieve the oxidation of the iron, or of a proportion of it, to the ferric form.
  • this may be achieved by the addition of a quantity of an oxidant, such as hydrogen peroxide, or by bubbling oxygen gas through the solution.
  • the oxidant is hydrogen peroxide it is preferred to use a quantity of from above 1 to 2 times the quantity theoretically required to convert the ferrous iron content of the solution, or the desired proportion of it into the ferric form.
  • Ambient temperature or an only slightly elevated temperature of, for example, up to 50° is preferred to reduce decomposition. It may be found adequate from the point of view of flocculant properties to oxidise less than all, for example from 50% to less than 100%, of the ferrous iron and in this case the quantity of the hydrogen peroxide may be adjusted accordingly.
  • the product of the present invention may also be sulphated if desired, either by introducing a water soluble sulphate or a solution containing sulphate values into the hydrochloric acid digestion liquor, into the reactants at a stage in the manufacture of that liquor, into the reactants during the digestion of the metallic iron and aluminium, into the polymeric product of the invention or at any other stage in the process. It has been found by the Applicants that the quantity of sulphate is preferably controlled for optimum performance at not more than 4.0% by weight calculated as SO4. A preferred range is from 0.5% to 3.5%.
  • a filter cake prepared by the neutralisation with magnesite of an acidic liquor derived from the sulphuric acid treatment of a montmorillonite clay mineral was mixed with hydrochloric acid in a cake:acid weight ratio of 1.5:1 giving a pH of 2.5.
  • the cake was digested at 70°C for 30 minutes with stirring and the liquor separated.
  • the liquor was then aged for 2 hours and 1.5% of aluminium metal was added to it and the temperature was them maintained at
  • the iron content of the solution was already in the ferric form.
  • the product of the example was a dark brown solution containing 78.3g/l AI2O3,
  • Example 1 was repeated with the sole difference that the aluminium addition was ommitted.
  • the product had a similar basicity to that of Example 1.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Separation Of Suspended Particles By Flocculating Agents (AREA)

Abstract

Un procédé de production d'un floculant à partir d'une liqueur aqueuse acide contenant des sels dissous d'aluminium et/ou de fer, tel qu'un liquide résiduaire provenant de l'activation acide d'un minéral argileux comme la montmorillonite, consiste à mettre en contact cette liqueur avec un matériau alcalin, tel que de la magnésite, pouvant réagir avec les sels dissous afin de précipiter les quantités d'aluminium et/ou de fer, à séparer de la liqueur le précipité sous forme de gâteau ou de boue, à traiter ce gâteau ou cette boue avec de l'acide chlorhydrique afin de dissoudre à nouveau les quantités d'aluminium et/ou de fer, en introduisant dans la liqueur de digestion, de préférence, de l'aluminium et/ou du fer métallique (dans le cas où la solution contient du fer ferreux, il est préférable de mettre en contact la solution avec un agent d'oxydation afin de convertir le fer sous la forme ferrique), et enfin à séparer de la solution résultante les matières solides en suspension. Le produit floculant, qui peut comprendre une solution d'un poly (aluminium et/ou fer) halogénure, donne une quantité résiduelle faible d'aluminium lorsqu'on l'utilise pour traiter l'eau. L'invention concerne également un nouveau poly(aluminium et/ou fer) halogénure contenant du magnésium.
PCT/GB1994/002181 1993-10-21 1994-10-06 Floculants WO1995011197A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU77899/94A AU7789994A (en) 1993-10-21 1994-10-06 Flocculants

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB939321734A GB9321734D0 (en) 1993-10-21 1993-10-21 Flocculants
GB9321734.7 1993-10-21

Publications (1)

Publication Number Publication Date
WO1995011197A1 true WO1995011197A1 (fr) 1995-04-27

Family

ID=10743915

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1994/002181 WO1995011197A1 (fr) 1993-10-21 1994-10-06 Floculants

Country Status (3)

Country Link
AU (1) AU7789994A (fr)
GB (1) GB9321734D0 (fr)
WO (1) WO1995011197A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
LT4384B (lt) 1996-12-12 1998-09-25 Akcinė bendrovė "ACHEMA" Aliuminio oksichlorido gamybos būdas
CN112591842A (zh) * 2020-12-11 2021-04-02 沈阳建筑大学 Nzvi-碳球/皂石复合材料的制备以及在污水治理领域的应用
CN115092998A (zh) * 2022-07-04 2022-09-23 庆阳新庄煤业有限公司新庄煤矿 一种用于回风大巷集水池的减盐减灰除煤尘絮凝剂

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50153799A (fr) * 1974-06-03 1975-12-11
US4566986A (en) * 1984-08-31 1986-01-28 Waldmann John J Flocculating agents and processes for making them
EP0181847A2 (fr) * 1984-11-14 1986-05-21 Olof Carlsson Procédé de préparation d'un agent flocculant
JPH0524849A (ja) * 1991-07-22 1993-02-02 Tokin Corp 高純度フエライト原料塩化物水溶液の製造方法
EP0532930A1 (fr) * 1991-09-16 1993-03-24 Deutsche Solvay-Werke Gesellschaft mit beschränkter Haftung Procédé de préparation de solutions aqueuses de sels d'aluminium basiques

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50153799A (fr) * 1974-06-03 1975-12-11
US4566986A (en) * 1984-08-31 1986-01-28 Waldmann John J Flocculating agents and processes for making them
EP0181847A2 (fr) * 1984-11-14 1986-05-21 Olof Carlsson Procédé de préparation d'un agent flocculant
JPH0524849A (ja) * 1991-07-22 1993-02-02 Tokin Corp 高純度フエライト原料塩化物水溶液の製造方法
EP0532930A1 (fr) * 1991-09-16 1993-03-24 Deutsche Solvay-Werke Gesellschaft mit beschränkter Haftung Procédé de préparation de solutions aqueuses de sels d'aluminium basiques

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, vol. 115, no. 14, 7 October 1991, Columbus, Ohio, US; abstract no. 139094, LARIN page 168; *
CHEMICAL ABSTRACTS, vol. 119, no. 4, 26 July 1993, Columbus, Ohio, US; abstract no. 31075H, CHIBA page 180; *
CHEMICAL ABSTRACTS, vol. 84, no. 20, 17 May 1976, Columbus, Ohio, US; abstract no. 137976B, page 148; *
KHIM. PROM-ST, no. 3, 1991, MOSKOW, pages 163 - 164 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
LT4384B (lt) 1996-12-12 1998-09-25 Akcinė bendrovė "ACHEMA" Aliuminio oksichlorido gamybos būdas
CN112591842A (zh) * 2020-12-11 2021-04-02 沈阳建筑大学 Nzvi-碳球/皂石复合材料的制备以及在污水治理领域的应用
CN115092998A (zh) * 2022-07-04 2022-09-23 庆阳新庄煤业有限公司新庄煤矿 一种用于回风大巷集水池的减盐减灰除煤尘絮凝剂

Also Published As

Publication number Publication date
AU7789994A (en) 1995-05-08
GB9321734D0 (en) 1993-12-15

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