EP0186552A2 - Verfahren und Vorrichtung für die Produktion einer Suspension von festen Teilchen, stabil in der Zeit - Google Patents

Verfahren und Vorrichtung für die Produktion einer Suspension von festen Teilchen, stabil in der Zeit Download PDF

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Publication number
EP0186552A2
EP0186552A2 EP85402321A EP85402321A EP0186552A2 EP 0186552 A2 EP0186552 A2 EP 0186552A2 EP 85402321 A EP85402321 A EP 85402321A EP 85402321 A EP85402321 A EP 85402321A EP 0186552 A2 EP0186552 A2 EP 0186552A2
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EP
European Patent Office
Prior art keywords
suspension
powder
mixture
suspensions
rotor
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Withdrawn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
EP85402321A
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English (en)
French (fr)
Inventor
Pascale Fournier
Joel Bertrand
Gilbert Casamatta
Dominique Bouchez
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.)
Elf Antar France
Original Assignee
Elf France SA
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 Elf France SA filed Critical Elf France SA
Publication of EP0186552A2 publication Critical patent/EP0186552A2/de
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/50—Mixing liquids with solids
    • B01F23/53—Mixing liquids with solids using driven stirrers

Definitions

  • the present invention relates to a method for obtaining suspensions of powders in one or more liquids, of stability, over time, greatly improved. It also includes an improved device for implementing this method, as well as a method for determining the stability of the suspensions.
  • agitation of the mixture which constitutes the fundamental operation of the preparation of a suspension, plays an important role, also various agitation techniques are used: mechanical agitation in a tank, with impellers of the turbine, propeller, screw type , helical ribbon, anchors, etc., or mechanical agitation in the pipeline, with in-line mixers, in particular with a turbine or screw.
  • a very effective method of agitation consists in subjecting the mixture to the action of ultrasonic waves, an expensive solution.
  • the present invention provides the advantage of making it possible to obtain suspensions of greatly improved stability, without the use of ultrasound or chemical additives.
  • the process according to the invention which consists in agitating the mixture of one or more liquids with a powder, to form a suspension of the latter in liquids, is characterized in that, the grain dimensions of the powder do not not exceeding 100 microns, stirring is carried out so as to subject the mixture to a shear of at least 8000 s -1 .
  • the shear produced within the mixture is from 10,000 to 60,000 s -1 , and above all from 15,000 to 40,000 s -1 .
  • the process optionally includes cooling, in order to avoid the temperature rising above that which could be detrimental to the stability of the components of the mixture.
  • the temperature of the mixture during stirring is set to the appropriate value. Most often it is between 20 ° and 100 ° C, when the treated mixture contains water, preferably between 60 ° and 95 ° C.
  • the condition of the grain size of the powder not exceeding 100 ⁇ m, is sufficient, it is preferable to operate with the finest powders possible. In particular, is it good to use a powder of which 80% have a particle size less than 60 ⁇ m and 50% less than 30 ⁇ m.
  • the proportions of solid and liquid, in the suspensions according to the invention can vary widely, but in general the weight content of solids does not exceed 50%, being most often between 20 and 50%, in particular between 30 and 45%.
  • the particular device for carrying out the method of the invention, is a mixer comprising a rotor rotating in a stator, a sufficiently narrow air gap being provided between these two parts, to produce shears of at least 8000 s -1 .
  • this mixer has the characteristics of a pump sucking the liquid upstream of the air gap to discharge it downstream of the latter.
  • one or more mobile blades are mounted transversely to the intake of the mixture; the blade or blades help to premix the materials to be treated, and promote the aspiration of the mixture in the space between the rotor and stator.
  • the width, in absolute value, of the air gap depends on the nature of the materials present, in particular on the viscosity of the mixture, the usual air gaps are generally around 0.5 to 2.5 mm, and most often 0.8 to 1.8 mm, for devices allowing a peripheral speed of the order of 10 m / s.
  • the invention can be applied to numerous materials, such as for example pigments, such as titanium, iron, alumina or zinc oxides, zinc sulfide, lead chromate, carbon black, lacquers and others, pesticides. as copper oxychloride, ethylene-bis dithiocarbamates of Zn and Mn, sulfur, etc., fuels, in particular coal powder.
  • the liquids in which the powders are dispersed can be, for example, vegetable or mineral oils, in particular cooked linseed oil, solutions of resins in organic solvents, hydrocarbons, petroleum or other liquid fuel, water and a hydrophobic organic fluid, in the form of an emulsion, as is for example the case for certain pesticidal compositions and for fuels based on carbon powder.
  • liquid mixtures for example compounds by weight of 40 to 50% of coal particles, 10 to 20% of water, the rest being a fraction of petroleum, in particular a heavy fuel oil; the suspension remains stable for at least 3 months at 60 ° C., despite the high water content, which - in the prior art - generally did not exceed 10%, in order to avoid too high a viscosity and rapid sedimentation of the dispersed solid.
  • More particularly excellent combustible, fluid suspensions, obtained by the process of the invention titrate 41 to 47% by weight of carbon in particles of 10 to 100 ⁇ m, 14 to 20% of water, the remainder being a hydrocarbon fraction , known as heavy fuel No. 2; the viscosity, which does not exceed 10 Pl at 60 ° C, allows easy pumping of this product.
  • the invention also relates to a new method for determining the stability of suspensions of powders in liquids. This process includes measuring the relative viscosity of the medium at different levels within the suspension, as a function of the storage times.
  • the diagram thus drawn, makes it possible to know the state of sedimentation of the suspension at a given time.
  • the long storage times of the suspensions are simulated by appropriate centrifugations; this allows to know, after minutes or hours of centrifugation, the sedimentation that a suspension would undergo after months or years of static rest.
  • plotted after m months of storage of suspensions with those given by suspensions of the same composition, at the same temperature, after centrifugation with a certain acceleration g, for e minutes, it can be established the correspondence between m and 0. It is thus possible, in accordance with the invention, to quickly anticipate the behavior that a suspension would have after months or years of rest.
  • the apparatus according to FIG. 1 is in fact a submersible centrifugal pump, with direct suction.
  • the motor 1 rotates the rotor 2 which rotates in the stator 3, from which it is separated by a narrow air gap 4.
  • the mixture to be treated enters the device through a suction channel 5 preferably located in the axis of the stator. 3. This channel is also crossed by a rod 5 which carries a blade 7 for the primary agitation of the mixture before aspiration 5.
  • the blade 7 being integral with the rotor 2, by means of the rod 6, it rotates in same time as the rotor driven by the motor 1.
  • Figure 1 shows only the mixer for the formation of a suspension, but it is understood that it is immersed in a container into which is introduced the desired liquid or liquids with the powder to be dispersed.
  • the bottom wall of the stator 3, and that of the rotor 2 are conical, so that the suction 5 ends at the top of the cone thus formed.
  • the characteristics of a stainless steel device, according to the invention making it possible to produce a few kilograms of suspension, no 1 to 5 kg per hour.
  • the temperature of the latter is then 90 ° C.
  • composition of the 3000 g of suspension obtained after cooling is determined, which gives by weight:
  • the maximum power consumed was 140 W per kg; the viscosity of the suspension at 60 ° C stood at 10000cP.
  • the speed at the periphery of the rotor reached about 10 m / s and the shear about 25000 s -1 .
  • Example 1 The procedure of Example 1 is applied to different quantities of the same components, which leads to obtaining a suspension of the weight composition: which keeps well for 3 months, while a similar suspension, prepared with a conventional agitator, producing a shear of 800 s -1 , undergoes almost complete sedimentation at the same time.
  • Example 1 The operations of Example 1 are repeated with the only difference that 0.2% of the dispersing agent known under the name ATLAS EL 1601 H is added to the mixture to be treated.
  • Example 3 The same dispersing agent as in Example 3 is used, at a rate of 0.2%, in a preparation according to Example 2. There is also a good improvement in stability over time. On the other hand, the addition of 0.2% dispersant, in the case of the suspension obtained with a shear of 800 s -1 , does not make it possible to have a stability of more than one month.
  • This determination is made by measuring the relative viscosity at different levels, within a stored suspension, after different durations.
  • the suspension being at rest in a tube with an internal diameter of 64 mm and a height of 126 mm, viscosity measurements are made using a Brookfield viscometer equipped with a needle. in T, and a Helipath foot allowing the vertical displacement of the needle; it therefore follows a helical path in the suspension. Since the viscosity is very sensitive to the carbon concentration of the suspension, an increase in this concentration results in an increase in the viscosity that the device detects.
  • the Brookfield viscometer used is of the LVTD type, with digital display, providing L indications from 0 to 100. Eight speeds, from 0.3 to 60 rpm, are available.
  • the needle is the standard T.F. model, whose crossbar measures 10.92 mm, the height being 114.3 mm and the diameter of 1.6 mm.
  • a recorder is coupled to the viscometer, allowing direct tracing of the viscosity profile.
  • the needle is lowered, continuously, to the bottom of the suspension, to then raise it to the surface of the latter.
  • the lower curve of h 100 / H corresponds to the levels (h 100 ) above the bottom, where the reading L of the viscometer is greater than or equal to 100.
  • the lower curve defines the height h 100 of the sediment formed by decantation supernatant (h o ).
  • the parameter h 100 is that for relatively thick suspensions, and in particular those which are the subject of the examples seen above, the apparent viscosity, corresponding to the value 100 of L, is quite strong and characterizes a thick sediment.
  • the apparent viscosity was around 90 ⁇ l for a speed gradient apparent of 0.05 s -1 , which indicates a sediment
  • Figure 4 relates to the particular embodiment of the invention, in which an accelerated aging of suspensions is achieved by centrifugation thereof before determining the sedimentation curves.
  • a month of storage at 60 ° C. could be simulated by a centrifugation of 30 minutes at the same temperature, with a centrifugal acceleration of 100 g at the bottom of the tube.
  • Fig. 4 shows two pairs of sedimentation curves I-I and II-II, the first of which correspond to natural aging and the second, II-II, to accelerated aging by centrifugation before determining the stability.
  • the abscissas in days refer to curves I-I and the abscissas in minutes relate to curves II-II of accelerated sedimentation. It can be seen, in the case of this example, that the storage of three months at 60 ° C. according to I produces substantially the same degree of sedimentation as a centrifugation of approximately 60 min at 100 g of acceleration at the bottom of the tube.

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  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Liquid Carbonaceous Fuels (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Colloid Chemistry (AREA)
EP85402321A 1984-12-07 1985-11-27 Verfahren und Vorrichtung für die Produktion einer Suspension von festen Teilchen, stabil in der Zeit Withdrawn EP0186552A2 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8418691A FR2574312A1 (fr) 1984-12-07 1984-12-07 Procede et appareil pour la production de suspensions de solides pulverulents dans des liquides, stables dans le temps
FR8418691 1984-12-07

Publications (1)

Publication Number Publication Date
EP0186552A2 true EP0186552A2 (de) 1986-07-02

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP85402321A Withdrawn EP0186552A2 (de) 1984-12-07 1985-11-27 Verfahren und Vorrichtung für die Produktion einer Suspension von festen Teilchen, stabil in der Zeit

Country Status (4)

Country Link
EP (1) EP0186552A2 (de)
DE (1) DE186552T1 (de)
FR (1) FR2574312A1 (de)
IT (1) IT1201505B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0845291A1 (de) * 1996-11-29 1998-06-03 Canadian Fracmaster Ltd Homogenisierapparat/Mischverfahren mit hoher Scherkraft zur Direkt-Hydratisierung von Frakturierungsflüssigkeiten und zur Direkt-Mischung von Zementschlamm
EP3697476B1 (de) 2017-10-18 2023-11-15 Eli Lilly and Company Beschleunigtes prüfverfahren für silikondrainage bei spritzen

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1496641A (en) * 1923-09-21 1924-06-03 Guy C Hurrell Mixing, incorporating, and disintegrating machine
US2688470A (en) * 1946-09-13 1954-09-07 Marco Company Inc Premixer and juicer unit
GB1500901A (en) * 1973-10-25 1978-02-15 Cementation Res Ltd Forming a colloidal suspension
US4175873A (en) * 1976-09-10 1979-11-27 Funken Co., Ltd. Process and apparatus for mechanically mixing two immiscible liquids and one or more other substances
JPS58117283A (ja) * 1981-12-29 1983-07-12 Electric Power Dev Co Ltd 石炭スラリ−組成物
US4477259A (en) * 1982-05-05 1984-10-16 Alfred University Research Foundation, Inc. Grinding mixture and process for preparing a slurry therefrom
JPS5926129A (ja) * 1982-08-05 1984-02-10 Konishiroku Photo Ind Co Ltd 分散液滴の製造装置

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0845291A1 (de) * 1996-11-29 1998-06-03 Canadian Fracmaster Ltd Homogenisierapparat/Mischverfahren mit hoher Scherkraft zur Direkt-Hydratisierung von Frakturierungsflüssigkeiten und zur Direkt-Mischung von Zementschlamm
EP3697476B1 (de) 2017-10-18 2023-11-15 Eli Lilly and Company Beschleunigtes prüfverfahren für silikondrainage bei spritzen

Also Published As

Publication number Publication date
DE186552T1 (de) 1986-11-27
IT1201505B (it) 1989-02-02
IT8523066A0 (it) 1985-12-03
FR2574312A1 (fr) 1986-06-13

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