EP1368503A2 - Method for increasing the dry residue in processed cyclone dust - Google Patents

Method for increasing the dry residue in processed cyclone dust

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Publication number
EP1368503A2
EP1368503A2 EP02727201A EP02727201A EP1368503A2 EP 1368503 A2 EP1368503 A2 EP 1368503A2 EP 02727201 A EP02727201 A EP 02727201A EP 02727201 A EP02727201 A EP 02727201A EP 1368503 A2 EP1368503 A2 EP 1368503A2
Authority
EP
European Patent Office
Prior art keywords
flocculant
sludge
cyclone dust
promoted
dry residue
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP02727201A
Other languages
German (de)
French (fr)
Inventor
Hans-Jörg BONATH
Georg Bombeck
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kronos Titan GmbH
Original Assignee
Kronos Titan GmbH
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Filing date
Publication date
Application filed by Kronos Titan GmbH filed Critical Kronos Titan GmbH
Publication of EP1368503A2 publication Critical patent/EP1368503A2/en
Withdrawn legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
    • A62D3/30—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents
    • A62D3/33—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents by chemical fixing the harmful substance, e.g. by chelation or complexation
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B34/00—Obtaining refractory metals
    • C22B34/10—Obtaining titanium, zirconium or hafnium
    • C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
    • C22B34/1218—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by dry processes
    • C22B34/1222—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by dry processes using a halogen containing agent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/006—Wet processes
    • C22B7/008—Wet processes by an alkaline or ammoniacal leaching
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/02—Working-up flue dust
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
    • A62D2101/40—Inorganic substances
    • A62D2101/43—Inorganic substances containing heavy metals, in the bonded or free state
    • 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
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the invention is directed to a process for the landfill-based work-up of heavy metal chlorides which accumulate as cyclone dust in the titanium dioxide production according to the chloride process, in which firstly insoluble constituents are separated from the cyclone dust which has been exposed to water or acids, then the pH of the solution by addition a neutralizing agent is raised in the pH range of 9 - 12, the heavy metals precipitate out as hydroxides, the hydroxides are thickened as sludge and are further dewatered.
  • the object of the invention is a process for the economical, large-scale processing of heavy metal chlorides which are obtained in the titanium ore chlorination, in particular regardless of the raw material used from the cyclone dust after removal of the inert components, a landfill product with a dry residue over 40%.
  • Floc is produced, which can be achieved by one - or preferably by a combination - of the following process improvements:
  • Thicken a (preferably anionic) flocculant mixed in Thicken a (preferably anionic) flocculant mixed in.
  • a (preferably cationic)
  • the filter pressure is preferably above 4 bar and the after-pressing pressure is above 10 bar.
  • the figure shows a process diagram for processing cyclone dust.
  • the volatile metal chlorides (1) formed in the chlorination reactor are cooled to such an extent that, apart from titanium tetrachloride, all are condensed together with the inert constituents - predominantly unreacted ore and coke particles - in a cyclone (2).
  • the titanium tetrachloride (3) which is still gaseous at this temperature, is then condensed (not shown here) and the remaining chlorination gases are passed to an exhaust gas cleaning system.
  • the solid mixture separated in the cyclone is referred to as cyclone dust (4).
  • a method according to the invention is outlined, with which none of the heavy metals present in the solution (10) is to be selectively recovered; all heavy metal ions are to be deposited as a substance which is no longer usable. They are converted into metal hydroxides by neutralization. It would be entirely possible to selectively separate individual ions or ion groups (for example iron or vanadium) at this point and to reprocess them. Such known process steps do not disturb and change the process according to the invention and are therefore not discussed further.
  • the neutralization is divided into two stages: a "quick" pre-neutralization and a readjustment.
  • the quick pre-neutralization takes place in a stirred (11) small premix tank (12) , whereby a rapid and above all spatially and temporally even increase in the pH value is achieved, and so there are no partial volumes even with fluctuations in the operational sequence, where the nucleation and floc formation are not optimal in terms of space and time.
  • the pH value increases in the pre-neutralization to 6 - 9.
  • a second (larger) neutralization tank (13) is provided, the suspension (14) emerging there has a uniform pH value between 9 - 12, preferably around 10.
  • the neutralization is preferably carried out with milk of lime (15) from a container (16.)
  • a pH value control (17) is indicated.
  • Filterability can be influenced favorably:
  • a first flocculant (22), preferably an anionic flocculant, can be added before the settling tank (18).
  • anionic flocculant preferably an anionic flocculant
  • Flocculants come, for example, copolymers of acrylamide and
  • the preferred amount is in the range 5-30 ppm, based on the total suspension amount.
  • a second flocculant (23), preferably a cationic flocculant, can also be added after thickening (18).
  • Cationic flocculants are, for example, cationic
  • the preferred amount is in the range 5-30 ppm, based on the thickened amount of sludge.
  • the drainage which is preferably carried out with a membrane filter press (21), also has an influence on the dry residue of the filter cake (26) to be deposited.
  • the folding pressure should be greater than 4 bar, preferably 10-15 bar.
  • the sludge is preferably repressed at 10-15 bar.
  • the dry residue in the filter cake can be increased to over 45%. This value is achieved regardless of the raw material used. It has been shown in the processes presented that both natural and artificial rutile as ore to be chlorinated produces a landfill-capable, non-thixotropic filter cake. With llmenite or with slag / rutile mixtures as a starting material with or without selective The advantage of working up the iron chloride lies solely in the high dry matter content of the filter cake, which is created when the metal chlorides are neutralized and worked up.
  • the filter cake is not thixotropic, the dry residue reaches 46.5%, the amount to be deposited is 1115 kg per t TiO 2 .
  • the filter cake is thixotropic (not suitable for landfill), the dry residue only reaches 26.9%, the amount to be deposited is 1270 kg per t TiO 2 .
  • the filter cake is not thixotropic, the dry residue is 38.6%, and the amount to be deposited is 627 kg per t TiO 2 .
  • a non-thixotropic filter cake with a 45% dry residue is obtained with the process according to the invention.
  • the amount to be deposited is now only 538 kg per t TiO 2 .

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Manufacturing & Machinery (AREA)
  • Toxicology (AREA)
  • General Health & Medical Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Processing Of Solid Wastes (AREA)
  • Treatment Of Sludge (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)

Abstract

During processing of cyclone dust (4) resulting from the chlorination of titanium ore, a disposable filter cake (26) having a dry residue of greater than 40 % (without inert portions serving as a supporting structure), regardless of whether ilmenite, slag or natural or artificial rutile or mixtures thereof were used as a raw material, is obtained when one or a combination of the following method steps is carried out: before increasing to a pH value ranging from 9 to 12 in a neutralization tank (13), a rapid neutralization step (12) is conducted whereby for all volume elements of the liquid, the same precipitation conditions can be maintained in a pH range of 6 to 9; a (preferably anionic) flocculation aid (22) is added before thickening, and; a (preferably cationic) second flocculation aid is mixed into the slurry after thickening. All measures improve the flocculation and render the processing more economical.

Description

Verfahren zur Erhöhung des Trockenrückstandes bei aufgearbeitetem Process for increasing the dry residue when processed
Zyklonstaubcyclone dust
Die Erfindung richtet sich auf ein Verfahren zur deponiefähigen Aufarbeitung von Schwermetallchloriden, die als Zyklonstaub bei der Titandioxid-Herstellung nach dem Chloridverfahren anfallen, wobei zunächst aus dem mit Wässern oder Säuren angeteigten Zyklonstaub unlösliche Bestandteile abgetrennt werden, anschließend der pH-Wert der Lösung durch Zugabe eines Neutralisationsmittels in den pH- Bereich von 9 - 12 angehoben wird, die Schwermetalle als Hydroxide ausfallen, die Hydroxide als Schlamm eingedickt und weiter entwässert werden.The invention is directed to a process for the landfill-based work-up of heavy metal chlorides which accumulate as cyclone dust in the titanium dioxide production according to the chloride process, in which firstly insoluble constituents are separated from the cyclone dust which has been exposed to water or acids, then the pH of the solution by addition a neutralizing agent is raised in the pH range of 9 - 12, the heavy metals precipitate out as hydroxides, the hydroxides are thickened as sludge and are further dewatered.
Ein solches Verfahren ist aus der DE 41 31 577 A1 bekannt. Dort ist dargestellt, dass die bei der Herstellung von Titandioxid nach dem Chloridverfahren unvermeidlich anfallenden (Schwer-)Metallchloride - außer Eisenchlorid - in deponiefähige Produkte umgewandelt werden müssen und man einen deponiefähigen Filterkuchen erhält, wenn man vor der Neutralisation des Schlammes die im Zyklonstaub auch enthaltenden inerten Bestandteile nicht abtrennt, aber damit in Kauf nimmt, dass das Deponievolumen erheblich größer und auf die weiterverwendbaren inerten Anteile des Zyklonstaubes verzichtet wird. Wenn man die in der DE 41 31 577 A1 gegebene Lehre anwendet, kann man auch ohne Inertmaterialien als Stützgerüst bei Schlacke oder Schlacke/Rutil- Mischungen mit überwiegendem Anteil an Schlacke als eingesetztem Rohstoff einen deponiegeeigneten Filterkuchen mit einem Trocken rückstand unter 40 %, üblicherweise um 35 %, erhalten. Wenn man beim Chloridprozess von natürlichem oder synthetischem Rutil ausgeht, sinkt bei der bekannten Aufarbeitung der Trockenrückstand bei der Schlammentwässerung aber unter . die Thixotropiegrenze: ein solcher Filterkuchen ist nicht handhabbar und deponiefähig.Such a method is known from DE 41 31 577 A1. It is shown there that the (heavy) metal chlorides - other than iron chloride - which are unavoidable in the production of the chloride process must be converted into landfill-capable products and a landfill-capable filter cake is obtained if one also contains those contained in the cyclone dust before neutralizing the sludge does not separate inert components, but thereby accepts that the landfill volume is considerably larger and that the reusable inert portions of the cyclone dust are dispensed with. If one applies the teaching given in DE 41 31 577 A1, it is also possible to use a landfill-suitable filter cake with a dry residue below 40%, usually around, without inert materials as a supporting structure for slag or slag / rutile mixtures with a predominant proportion of slag as the raw material used 35% received. If natural or synthetic rutile is used as the starting point in the chloride process, the dry residue in the sludge dewatering process will drop under the known process. the thixotropy limit: such a filter cake cannot be handled and is suitable for landfill.
Aufgabe der Erfindung ist ein Verfahren zur wirtschaftlichen, großtechnischen Aufarbeitung von Schwermetallchloriden, die bei der Titanerzchlorierung anfallen, insbesondere soll unabhängig von dem eingesetzten Rohstoff aus dem Zyklonstaub nach Abtrennung der inerten Bestandteile ein deponiefähiges Produkt mit einem Trockenrückstand über 40 % erhalten werden.The object of the invention is a process for the economical, large-scale processing of heavy metal chlorides which are obtained in the titanium ore chlorination, in particular regardless of the raw material used from the cyclone dust after removal of the inert components, a landfill product with a dry residue over 40%.
Die Aufgabe wird dadurch gelöst, dass bei der Prozessführung eine gutfiltrierbareThe task is solved in that the process control is easy to filter
Flocke erzeugt wird, was durch eine - oder bevorzugt durch eine Kombination - der folgenden Verfahrensverbesserungen erreicht werden kann:Floc is produced, which can be achieved by one - or preferably by a combination - of the following process improvements:
Vor der Einstellung des pH-Wertes auf 9 - 12 in der Neutralisationsstufe erfolgt eine schnelle und homogene Vorneutralisation auf einen pH-Wert im Bereich 6 -Before setting the pH to 9 - 12 in the neutralization stage, a quick and homogeneous pre-neutralization to a pH in the range 6 -
9.9th
In die Suspension mit den gefällten Schwermetallhydroxiden wird vor demIn the suspension with the precipitated heavy metal hydroxides before
Eindicken ein (vorzugsweise anionisches) Flockungshilfsmittel eingemischt.Thicken a (preferably anionic) flocculant mixed in.
In den eingedickten Schlamm wird ein (vorzugsweise kationisches)In the thickened sludge, a (preferably cationic)
Flockungshilfsmittel eingemischt.Flocculant mixed in.
Es ist vorteilhaft, den Schlamm in einer Membranfilterpresse zu entwässern, bevorzugt liegt der Filterdruck über 4 bar, der Nachpressdruck über 10 bar.It is advantageous to dewater the sludge in a membrane filter press; the filter pressure is preferably above 4 bar and the after-pressing pressure is above 10 bar.
Durch jede dieser Maßnahmen wird einzeln - und erst recht bei einer KombinationEach of these measures is individual - and even more so when combined
- unabhängig von dem in dem Chlorierungsreaktor eingespeisten Rohstoff - ohne- regardless of the raw material fed into the chlorination reactor - without
Inertmaterialien als Stützgerüst ein deponiefähiger Filterkuchen mit einemInert materials as a scaffold a filter cake with a landfill
Trockenrückstand über 40 Gew.-% erhalten.Dry residue obtained over 40 wt .-%.
Die Erfindung ist in der Zeichnung dargestellt und im Folgenden weiter erläutert und beispielhaft beschrieben.The invention is illustrated in the drawing and further explained and described below by way of example.
Die Figur zeigt ein Verfahrensschema zur Aufarbeitung von Zyklonstaub.The figure shows a process diagram for processing cyclone dust.
Bei der Titandioxidherstellung nach dem Chloridprozess werden die im Chlorierungsreaktor gebildeten, flüchtigen Metallchloride (1 ) so weit abgekühlt, dass außer Titantetrachlorid alle in kondensierter Form gemeinsam mit den inerten Bestandteilen - vorwiegend unreagierte Erz- und Kokspartikel - in einem Zyklon (2) abgeschieden werden. Das bei dieser Temperatur noch gasförmige Titantetrachlorid (3) wird (hier nicht dargestellt) anschließend kondensiert und die verbleibenden Chlorierungsabgase einer Abgasreinigung zugeführt. Das im Zyklon abgeschiedene Feststoffgemisch wird als Zyklonstaub (4) bezeichnet. Beim Anteigen des Zyklonstaubes (4) in einem Behälter (5) durch Zugabe von Wasser und/oder sauren Prozessabwässern (6), die im Betrieb anfallen und wegen dieser Verwendung nicht aufwendig gereinigt werden müssen, entsteht eine saure Suspension (7): alle Metallchloride sind gelöst, die inerten Feststoffpartikel (8), Koks und unreagiertes Erz, bleiben unverändert und sind weiterverwendbar. Sie können problemlos in einem Filter (9) abgetrennt werden.When producing titanium dioxide after the chloride process, the volatile metal chlorides (1) formed in the chlorination reactor are cooled to such an extent that, apart from titanium tetrachloride, all are condensed together with the inert constituents - predominantly unreacted ore and coke particles - in a cyclone (2). The titanium tetrachloride (3), which is still gaseous at this temperature, is then condensed (not shown here) and the remaining chlorination gases are passed to an exhaust gas cleaning system. The solid mixture separated in the cyclone is referred to as cyclone dust (4). When the cyclone dust (4) rises in a container (5) by adding water and / or acidic process wastewater (6) that is generated during operation and does not have to be cleaned due to this use, an acidic suspension (7) is formed: all metal chlorides are dissolved, the inert solid particles (8), coke and unreacted ore remain unchanged and can be reused. They can easily be separated in a filter (9).
In der Figur ist ein erfindungsgemäßes Verfahren skizziert, mit dem keines der in der Lösung (10) vorhandenen Schwermetalle selektiv wiedergewonnen werden soll, alle Schwermetallionen sollen als nicht mehr brauchbarer Stoff deponiert werden. Sie werden durch Neutralisation in Metallhydroxide überführt. Es wäre durchaus möglich, an dieser Stelle einzelne Ionen oder lonengruppen (beispielsweise Eisen oder Vanadium) selektiv abzutrennen und einer Wiederaufarbeitung zuzuführen. Solche an sich bekannten Verfahrensschritte stören und verändern das erfindungsgemäße Verfahren nicht und werden daher nicht weiter erörtert.In the figure, a method according to the invention is outlined, with which none of the heavy metals present in the solution (10) is to be selectively recovered; all heavy metal ions are to be deposited as a substance which is no longer usable. They are converted into metal hydroxides by neutralization. It would be entirely possible to selectively separate individual ions or ion groups (for example iron or vanadium) at this point and to reprocess them. Such known process steps do not disturb and change the process according to the invention and are therefore not discussed further.
Es hat sich als besonders günstig für die am Ende des Prozesses erforderliche Entwässerung herausgestellt, wenn die Neutralisation in 2 Stufen aufgeteilt wird: in eine „schnelle" Vorneutralisation und eine Nacheinstellung. Die schnelle Vorneutralisation erfolgt in einem gerührten (11 ) kleinen Vormischtank (12), wodurch eine rasche und vor allem räumlich und zeitlich gleichmäßige Anhebung des pH-Wertes erreicht wird und so auch bei Schwankungen im Betriebsablauf keine Teilvolumina entstehen, wo die Keim- und Flockenbildung räumlich und zeitlich nicht optimal erfolgen. Der pH-Wert steigt in der Vorneutralisation auf 6 - 9 an. Zur Stabilisierung und Feineinstellung ist ein zweiter (größerer) Neutralisationstank (13) vorgesehen; die dort austretende Suspension (14) hat einen einheitlichen pH-Wert zwischen 9 - 12, bevorzugt um 10. Die Neutralisation erfolgt bevorzugt mit Kalkmilch (15) aus einem Behälter (16). Eine pH-Wert- Regelung (17) ist angedeutet.It has proven to be particularly favorable for the dewatering required at the end of the process if the neutralization is divided into two stages: a "quick" pre-neutralization and a readjustment. The quick pre-neutralization takes place in a stirred (11) small premix tank (12) , whereby a rapid and above all spatially and temporally even increase in the pH value is achieved, and so there are no partial volumes even with fluctuations in the operational sequence, where the nucleation and floc formation are not optimal in terms of space and time. The pH value increases in the pre-neutralization to 6 - 9. For stabilization and fine adjustment, a second (larger) neutralization tank (13) is provided, the suspension (14) emerging there has a uniform pH value between 9 - 12, preferably around 10. The neutralization is preferably carried out with milk of lime (15) from a container (16.) A pH value control (17) is indicated.
Sämtliche Schwermetallionen aus dem Zyklonstaub werden durch die Neutralisation als Hydroxide ausgefällt. Die Zwischenschaltung des gerührten Vormischtankes (12) hat Einfluss auf die Flockenbildung, es scheint vor allem die Gleichmäßigkeit der Flocke positiv beeinflusst zu werden.All heavy metal ions from the cyclone dust are removed by the Neutralization precipitated as hydroxides. The interposition of the stirred pre-mixing tank (12) has an influence on the formation of flakes, and above all the uniformity of the flakes seems to be positively influenced.
Aus der Suspension (14) setzt sich in einem Eindicker (18) ein Schlamm (19) ab, der mit einer Pumpe (20) über einen Behälter (24) und eine Pumpe (25) zu einer Filterpresse (21 ) gefördert wird.A sludge (19) settles out of the suspension (14) in a thickener (18), which is conveyed by a pump (20) via a container (24) and a pump (25) to a filter press (21).
Durch zwei weitere Maßnahmen kann die Flockenbildung mit Einfluss auf dieTwo additional measures can be used to influence the formation of flakes
Filtrierbarkeit günstig beeinflusst werden:Filterability can be influenced favorably:
Vor dem Absetztank (18) kann ein erstes Flockungshilfsmittel (22), bevorzugt ein anionisches Flockungshilfsmittel, zugegeben werden. Als anionischeA first flocculant (22), preferably an anionic flocculant, can be added before the settling tank (18). As anionic
Flockungshilfsmittel kommen beispielsweise Copolymere von Acrylamid undFlocculants come, for example, copolymers of acrylamide and
Natriumacrylat in Frage, die bevorzugte Menge liegt im Bereich 5 - 30 ppm, bezogen auf die Gesamtsuspensionsmenge.Sodium acrylate in question, the preferred amount is in the range 5-30 ppm, based on the total suspension amount.
Auch nach dem Eindicken (18) kann ein zweites Flockungshilfsmittel (23), bevorzugt ein kationisches Flockungshilfsmittel, zugegeben werden.A second flocculant (23), preferably a cationic flocculant, can also be added after thickening (18).
Als kationisches Flockungshilfsmittel kommen beispielsweise kationischeCationic flocculants are, for example, cationic
Acrylamidcopolymere in Frage, die bevorzugte Menge liegt im Bereich 5 - 30 ppm, bezogen auf die eingedickte Schlammmenge.Acrylamide copolymers in question, the preferred amount is in the range 5-30 ppm, based on the thickened amount of sludge.
Von Einfluss auf den Trockenrückstand des zu deponierenden Filterkuchens (26) ist auch noch die Entwässerung, die bevorzugt mit einer Membranfilterpresse (21 ) erfolgt. Der -Fältdruck sollte größer 4 bar, bevorzugt 10 - 15 bar sein. Das Nachpressen des Schlammes erfolgt bevorzugt bei 10 - 15 bar.The drainage, which is preferably carried out with a membrane filter press (21), also has an influence on the dry residue of the filter cake (26) to be deposited. The folding pressure should be greater than 4 bar, preferably 10-15 bar. The sludge is preferably repressed at 10-15 bar.
Nach diesen beispielhaften Verfahren kann der Trockenrückstand im Filterkuchen auf über 45 % angehoben werden. Dieser Wert wird unabhängig vom eingesetzten Rohstoff erreicht. Es hat sich bei den dargestellten Verfahren gezeigt, dass sowohl bei natürlichem als auch bei künstlichem Rutil als zu chlorierendem Erz ein deponiefähiger, nicht thixotroper Filterkuchen entsteht. Bei llmenit oder bei Schlacke/Rutil-Mischungen als Ausgangsstoff mit oder ohne selektiver Aufarbeitung des Eisenchlorids liegt der Vorteil ■ allein in dem hohen Trockensubstanzgehalt des Filterkuchens, der bei der Neutralisation und Aufarbeitung der Metallchloride entsteht.According to these exemplary processes, the dry residue in the filter cake can be increased to over 45%. This value is achieved regardless of the raw material used. It has been shown in the processes presented that both natural and artificial rutile as ore to be chlorinated produces a landfill-capable, non-thixotropic filter cake. With llmenite or with slag / rutile mixtures as a starting material with or without selective The advantage of working up the iron chloride lies solely in the high dry matter content of the filter cake, which is created when the metal chlorides are neutralized and worked up.
Nachfolgend die erzielbaren Trockenrückstände und zu deponierenden Mengen bei reinem Rutileinsatz:The following shows the achievable dry residues and quantities to be deposited with pure rutile use:
Verfahren A (Stand der Technik)Process A (prior art)
Bei einer Neutralisation der Originalsuspension ohne Abtrennung der inerten Bestandteile ist der Filterkuchen nicht thixotrop, der Trockenrückstand erreicht 46,5 %, die zu deponierende Menge liegt bei 1115 kg pro t TiO2.If the original suspension is neutralized without separating the inert constituents, the filter cake is not thixotropic, the dry residue reaches 46.5%, the amount to be deposited is 1115 kg per t TiO 2 .
Verfahren B (Stand der Technik)Method B (state of the art)
Werden aus der Suspension im Verfahren A die inerten Anteile entfernt, ist der Filterkuchen thixotrop (nicht deponiefähig), der Trockenrückstand erreicht nur 26,9 %, die zu deponierende Menge beträgt 1270 kg pro t TiO2.If the inert portions are removed from the suspension in process A, the filter cake is thixotropic (not suitable for landfill), the dry residue only reaches 26.9%, the amount to be deposited is 1270 kg per t TiO 2 .
Verfahren C (Stand der Technik)Process C (prior art)
Bei einer Behandlung der Suspension nach dem in der DE 41 31 577 A1 beschriebenen Verfahren III ist der Filterkuchen nicht thixotrop, der Trockenrückstand beträgt 38,6%, die zu deponierende Menge liegt bei 627 kg pro t Ti02.When the suspension is treated according to method III described in DE 41 31 577 A1, the filter cake is not thixotropic, the dry residue is 38.6%, and the amount to be deposited is 627 kg per t TiO 2 .
Verfahren DProcedure D
Mit dem erfindungsgemäßen Verfahren wird ein nicht thixotroper Filterkuchen mit 45 % Trockenrückstand erhalten. Die zu deponierende Menge beträgt nur noch 538 kg pro t TiO2. A non-thixotropic filter cake with a 45% dry residue is obtained with the process according to the invention. The amount to be deposited is now only 538 kg per t TiO 2 .

Claims

Patentansprüche claims
1. Verfahren zur deponiefähigen Aufarbeitung von Schwermetallchloriden, die als Zyklonstaub bei der Titandioxid-Herstellung nach dem Chloridverfahren anfallen, wobei zunächst aus dem mit Wässern oder Säuren angeteigten Zyklonstaub unlösliche Bestandteile abgetrennt werden, anschließend der pH-Wert der Lösung durch Zugabe eines Neutralisationsmittels in den pH- Bereich von 9 - 12 angehoben wird, die Schwermetalle als Hydroxide ausfallen, die Hydroxide als Schlamm eingedickt und weiter entwässert werden, dadurch gekennzeichnet, dass durch eine verbesserte Flockenbildung der Trockenrückstand des zu deponierenden Schlammes auf über 40 Gew.-% angehoben wird.1. A process for the landfill-based processing of heavy metal chlorides, which are obtained as cyclone dust during the titanium dioxide production according to the chloride process, whereby initially insoluble constituents are separated from the cyclone dust, which has been exposed to water or acids, then the pH of the solution by adding a neutralizing agent to the pH range from 9 to 12 is raised, the heavy metals precipitate as hydroxides, the hydroxides are thickened as sludge and are further dewatered, characterized in that the dry residue of the sludge to be deposited is increased to over 40% by weight through improved flocculation.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die verbesserte Flockenbildung durch eine der pH-Feineinstellung vorgeschaltete schnelle pH-Anhebung bis pH 9 gefördert wird, wodurch es in allen Volumenelementen der Lösung zu einer gleichmäßigen und schnellen pH- Wert-Einstellung kommt.2. The method according to claim 1, characterized in that the improved flake formation is promoted by a rapid pH increase up to pH 9 upstream of the pH fine adjustment, as a result of which a uniform and rapid pH value adjustment occurs in all volume elements of the solution.
3. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die verbesserte Flockenbildung durch Zugabe eines ersten Flockungshilfsmittels vor dem Eindicken in dem Absetztank gefördert wird.3. The method according to claim 1, characterized in that the improved flocculation is promoted by adding a first flocculant before thickening in the settling tank.
4. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die verbesserte Flockenbildung durch Zugabe eines zweiten Flockungshilfsmittels vor der Entwässerung des Schlammes gefördert wird.4. The method according to claim 1, characterized in that the improved flocculation is promoted by adding a second flocculant before dewatering the sludge.
5. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die verbesserte Flockenbildung durch Kombination von zwei oder allen drei Maßnahmen nach den Ansprüchen 2 - 4 gefördert wird.5. The method according to claim 1, characterized in that the improved flocculation is promoted by combining two or all three measures according to claims 2-4.
6. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass als erstes Flockungshilfsmittel ein anionisches Flockungshilfsmittel verwendet wird.6. The method according to claim 3, characterized in that as the first Flocculant Anionic flocculant is used.
7. Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass als zweites Flockungshilfsmittel ein kationisches Flockungshilfsmittel verwendet wird.7. The method according to claim 4, characterized in that a cationic flocculant is used as the second flocculant.
8. Verfahren nach einem oder mehreren der Ansprüche 1 - 6, dadurch gekennzeichnet, dass der Schlamm mit einer Membranfilterpresse entwässert wird.8. The method according to one or more of claims 1-6, characterized in that the sludge is dewatered with a membrane filter press.
9. Verfahren nach Anspruch 7, dadurch gekennzeichnet, dass der Filterdruck in der Membranfilterpresse über 4 bar liegt.9. The method according to claim 7, characterized in that the filter pressure in the membrane filter press is above 4 bar.
10. Verfahren nach Anspruch 7 oder 8, dadurch gekennzeichnet, dass der Nachpressdruck in der Membranfilterpresse über 10 bar liegt. 10. The method according to claim 7 or 8, characterized in that the secondary pressure in the membrane filter press is above 10 bar.
EP02727201A 2001-03-13 2002-03-08 Method for increasing the dry residue in processed cyclone dust Withdrawn EP1368503A2 (en)

Applications Claiming Priority (3)

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DE10111895 2001-03-13
DE2001111895 DE10111895A1 (en) 2001-03-13 2001-03-13 Process for increasing the dry residue in processed cyclone dust
PCT/DE2002/000844 WO2002072205A2 (en) 2001-03-13 2002-03-08 Method for increasing the dry residue in wet-processed cyclone dust of the chlorination of titanium ore

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TWI243697B (en) 2005-11-21
DE10111895A1 (en) 2002-09-19
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JP2004528162A (en) 2004-09-16
WO2002072205A3 (en) 2003-04-17
MXPA03007247A (en) 2003-12-04
US20040136889A1 (en) 2004-07-15
CA2438311A1 (en) 2002-09-19

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