DE1914323A1 - Vermiculite mixtures, their production and use - Google Patents

Description

PATENT LAWYERS

Dr. D. Thomson

Dipl.-Chem.

H. Tiedtke

Dipl, -lng.

G. BüMbic

Dipl.-Chem.

1 .QI / O O Q

8000 MUNICH 2

VAL 33

TELEPHONE 0811/226894 TELEGRAM ADDRESS: THOPATENT

Munich March 20, 1969 case 6l 508 / T 3052

"* ■

/ "

Mandoval Limited London / Great Britain

Vermiculite mixtures, their production and use

The invention relates to a new mixture made from vermiculite, a process for the preparation this new mixture and its uses.

According to one embodiment of the invention is.als a new mixture of delaminated flaked vermiculite is provided.

The delaminated exfoliated vermiculite is said to have flaky particles. The aspect ratio from flake width to flake thickness should be preferred

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be at least ^>: 1 and in particular 4: 1 or more. The term "scaly" is defined in "British Standard" 812 ".

Natural vermiculite and flaked vermiculite are already well known commercial items.

Vermiculite is a natural mineral of the mica family. In the mined state, vermiculite consists of scales containing microscopic water particles. A typical chemical analysis of this vermiculite is given below .

"Chemical Analysis

SiO ₂ 59.57 % TiO ₂ 1.25 Al ₂ OJ 12.08 Pe ₂ O ₃ . 5.45 FeO 1.17 MnO 0.50 MgO 25.57 CaO 1.46 Na ₂ O 0.80 K ₂ O 2.46 H ₂ O + 105 ° C 5.18 H ₂ O-105 ^° C 6.02 CO ₂ 0.60 ^P 2 ° 5 0.15

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Li ₂ 0 ZrO 2 Cr ₂
VoO • ζ - NOK CoO BaO Cl P.

0.05 nothing

0.03 0.02 nothing 0.02 0.18

During sudden subjecting it to high temperatures (700 ° - 1100 ⁰ C), the scales of the crude vermiculite sheets under Ausdehnung.auf a multiple of its original volume due to the formation of Dampfauf pushing aside the leaflets of the scales when it is expelled.

Exfoliated vermiculite consists of accordion-like Grains containing millions of tiny layers of air to which exfoliated vermiculite is tall Thanks to its insulation value and its light weight.

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When flaked vermiculite is subjected to grinding under conventional conditions, the material can •. Possibly into a powder in the form of a fine flour be reduced. If this procedure, which in,; any usual technical grinding device can be carried out, is stopped before the powdery stage is achieved, a test shows that there is a reduction in all dimensions of the exfoliated vermiculite particles has been effected. However, when the flaked vermiculite is in a suitable device, e.g. Hammer mill, which is ground at extremely low loads, is there instead of reducing all particle dimensions possible him. to particles containing a relatively small number of platelets for manufacture of the new mixture of "delaminated exfoliated vermiculite".

This embodiment of the invention is described below explained in more detail with reference to figures, FIG. 1 schematically showing the method of

Exfoliation of a piece of raw vermiculite shows

Fig. 2 shows an enlarged view of a large piece of exfoliated vermiculite;

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Fig. J shows the manner in which exfoliated Vermiculite tends to build up in relation to a flat surface,

Pig. 4 schematically 'the process for Delamination. of a piece peeled off Vermiculite shows

Pig. 5 a piece of 'delaminated ade leafed Vermiculite shows and

. Figure 6 shows the manner in which delaminated exfoliated .Vermiculite tends to build up in relation to a flat surface.

An examination of the natural vermiculite shows that, like mica, it is a scale-like material that is composed of leaflets. However, if the leaflets are expanded by heating, these leaflets will separate not to such an extent that all of the structure is lost. The procedure of exfoliation is. shown schematically in FIG. It is important to yourself to remember that the process of exfoliation does not change the surface area of the leaflets, just the distance between them.

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In Pig. 2 is one made from a photograph Drawing of a large piece of flaked vermiculite shown. As shown in this drawing, the length C of this particle is considerably greater than the dimensions a and b of the leaflets. This has the effect that it takes on the peculiarity when dropped or when otherwise applied to a fairly flat surface, that its components, the leaflets, are arranged vertically or approximately vertically to the surface, against which it comes to rest. This is shown in FIG. 3. Hence any coatings made using this Form of vermiculite would be made, porous as fluids both Liquid as well as gas - through or into which particles can penetrate. This fact can be used to advantage will. For example, the addition of flaked vermiculite to plaster causes it to retain water, and thus does its application to a strongly absorbent surface, e.g. concrete, is entirely possible. However, on the other hand, is every coating produced in this way is porous and therefore allows both liquids and gases, to penetrate them. As a result of the content of empty spaces it is also to be used as an isolation medium. This form of coating is not new.

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The delamination and the product d method according to the invention are shown in Figures K and 5. FIG.

As shown in Figure 4, the dimensions of the edges of the leaflets are not changed except for a small degree of delamination. By grading vermiculite for size by sieving the scales (generally in the mine), this means that the delaminated exfoliated product is about the same size as the original vermiculite scales '. Furthermore, as the figure shows, these flakes are still exfoliated (further heating generally does not exfoliate them) and in this way retain the thermal insulation properties of the starting material to a certain extent. However, the more significant difference emerges from a comparison of FIGS. 2 and 5. From these schematic representations it can be seen that - while the edge dimensions a and b are the same or of the same order of magnitude - the thickness p extension c in Fig. 2 very much e than the thickness dimension d in 'Fig. 5 is. This has the significant con- li / sequence that dre leaflets when dropped on a rather flat surface or applied in another way, the Eigenart- assume that its layers are arranged parallel or substantially parallel to the surface ·.

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This is in Pig. 6 shown. · Therefore, coatings can be made with this material that are not porous because, when used in large quantities, these leaflets will overlap and lie against each other and form an almost continuous film substantially parallel to the "face. By use." With a suitable binder, this layer can be made so that it is quite close to a surface, e.g., a surface of pyrophoric freshly exposed Coal in a mine adheres and is effective against penetration of both gas and liquid seals. By using a special binder, a coating can be created, which can expand and contract without cracking through it; this form of coating can ' used on surfaces that are subject to slow thermal movement, e.g. a power station boiler.

According to a further embodiment of the invention there is provided a method of making delaminated exfoliated vermiculite in which exfoliated Vermiculite in a mill with a single shear effect on the exfoliated vermiculite particles is treated.

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The mill used is preferably a hammer mill of the type described below ..

According to the invention it has been found that raised Vermiculite delaminates in almost every type of technical mill that exert a simple twisting action and perform the least labor on the scales made in this way. According to the invention the use of a hammer mill is preferred for this purpose, which is operated under conditions such that there is a minimum of crushing action on the particles is exercised, either by being hit by more than one hammer or by abrasion between the particle. To achieve this, the mill is operated under low load conditions, with sfch to each When there is little material in the mill and operated in such a way that the hammers rotate considerably more slowly, than is generally the case.

The type of mill that is preferred according to the invention is a hammer mill of the type shown schematically in Figures 7 and 8, wherein

7 schematically shows the principle of the hammer mill shows and

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Pig. Figure 8 shows the type of screen through which the product is withdrawn from the mill.

As shown in FIGS. 7 and 8, a rotor 11, to which various hammers 12 are connected, is located in a milling chamber 10. The connection is not rigid and the hammers can move with respect to the rotor; when "rotates the rotor, causing the centrifugal force that they assume a substantially radial orientation, but with a narrow gap between the hammer head 1J> and the" grinding chamber. The upper half 10A of the "grinding chamber" is generally solid (it is generally removable for maintenance, cleaning, etc.) while the "lower part 10B" is a sieve, often of a herringbone pattern. This is shown in greater detail in FIG. The material is fed into the mill through tube 14, the simplest type being gravity feed from a pre-hopper ... This system is somewhat uncontrollable and generally an Archimedean screw device is used, the speed of which is variable .

During operation, the rotor turns in the direction shown. In this way, the exfoliated vermiculite particles, as soon as they enter the mill, struck by one of the hammers; this causes the leaflets

Tl

-u-

separated, which then - as a result of the tangential speed imparted by the hammer blow - through the sieve slots fall. The feeding speed is adjusted in such a way that, firstly, multiple collisions of a given particle does not 'enter with the hammers and, secondly, that there is not enough material in the Grinding chamber is present at any point in time for the tangential momentum given to a particle to cause that it hits another particle and thus causes abrasion between the particles. These two Conditions are achieved when using such a mill of the usual type for powder production.

By way of illustration, comparative conditions are given for the production of delaminated, sebj-dotted vermiculite and for the production of vermiculite powder in the same mill given below:

(a) Mill: "Mikro Pulverizer Nr.ISH," manufactured by.

Mikropul Ltd., England.

(b) Mill type: rotary hammer mill (as schematically in

7) ] with a chamber diameter of 20.3 cm (8 "); the gap between the hammers and the housing is about 0.025 cm (.010"). The lower one

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ORIGINAL INSPECTED

19 H 32 3

-IrS-

Half of the grinding chamber is a herringbone-like sieve (shown schematically •. in Fig. 8); the feed to the mill takes place

by means of a funnel and a Archimedean snail. Both the feed speed and the speed of rotation of the mill (rpm) and the size of the sieve slot can be varied.

(c) Operating Conditions.

(i) Charging: flaked vermiculite from nomi-

nell 1/8 "to 3 / Ϊ6" (3.18 to 4.7β mm) (ii) Mill Settings.

for delamination for powders

Loading speed in ■ kg / h (lb / hr.)

Sieve slots in mm

Mill U.p.m. (r.p.m.)

(400)

4.76 12.7
(3/16 "χ 1/2")

2,880

(iii) Products, sieve analysis (wt. $).

544 (1,200)

4.76 χ 12; 7 (3/16 "χ 1/2")

9,000

Passage
(passing ^

76 mm (3 / l6 Delamination. after ', Powder. after Meshes before '100 before 100. 4, ti ) 100 98.3 100 100 7th ti 92.8 46.8 92.8 100 14th It 24.8 24.3 24.8 100 25th 4.0 11.5 4.0 97.0 52 1.2 1.2

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Sieves: Standard according to BSS 410.

It is also noted that a 7-mesh screen is one square hole J5.18mm (1/8 ") on a side and about 4/76 mm (3/16 ") diagonal; with a 14-mesh screen the side length is 1.59 mm (l / l6 ") and the diagonal 2.38 mm (3/52"). Hence surrendered clear conclusions from these values:

(a) only about 12 % powder is formed;

(b) 33ur about 25 $ of the leaflets have been considered very greatly reduced their size as _they; - to go through a 4 "76 oil sieve (3/16"), originally had to measure 4.76 x 4.76 mm (3/16 "; 3c .: 3/16) or less; in fact, 20 % were smaller than 5.1 x 3.18 mm (l / 8 χ 1/8) (ie., they passed a 14, but not a ZS machine sieve).

According to yet another argument, s'forrti

of the invention is a sealing or coating mixture created, the. "delaminated exfoliated vermiculite · and contains a binder or binders.

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A filler is preferably one of these fillers included in the mix.

Preferably "the average of the largest dimension of the delarainierten exfoliated vermieulite is 6j35 mm (one-quarter of an inch) or less *

Such a diet mixture should, in order to be actually usable . especially for use in mines ^ ideally have the properties given below.

1. Good adhesion to various substrate surfaces (rock, coal, steel / wood, plastics, etc.) that may have some surface dust.

2. Non-flammable, e.g. when tested in accordance with BS 1953. "

3. High impermeability, especially to gases.

4. Non-breaking properties on impact, e.g. when passing machines, and good abrasion resistance.

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5. Good dimensional stability, β. Good fire protection.

7.. No health risk before, during or after an application.

8. Variable setting time of almost instantaneous, up to several hours.

9. Good resistance to mass, i.e. while it does not have to be impermeable to water, · it must not be decomposed by water.

This mixture can be used in two different ways in mining operations. First it can be applied to the interior surfaces together with a suitable system a degradation as a sealant ■ be applied. When this material is used in this way it causes it in sharp contrast to the known Sealing or coating means a "coating of low permeability to oxygen (or air) and mine gases. The most widely used type of known material is that of plaster of paris; Coatings based on the material according to the invention are 6 to 10 times less permeable to oxygen.

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Second, where there is a need to seal a mine, such as when a fire has occurred in a mine; or more commonly, a plug or plug is formed to regulate the ventilation air. The _v new mixture can be used for closures and, if desired, further materials for Grundbe layering mixture are added to the erforder-P to provide lent strength properties .. The closure must be capable of any explosion can take place to take up without either breaking open or moving lengthways into the

Ϊ -

construction moves

In the approaches given below, the Abbreviation D.e.v. used for delaminated exfoliated vermiculite.

Coating approach

Basic mixture j Binder: 1 part by volume

compatible filler; ο to

3 parts by volume

B * e-v ^ i.l to 6 parts by volume.

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The binder can be ordinary portland cement, white portland cement, sulfate-resistant portland cement, fast-setting portland cement, calcium oxide (lime) or Alumina zemerite '. .. ^. (where in the case of Calcium oxide strength is only developed over time) or a mixture of some of the above Be fabrics.

The filler can be any suitable compatible Be material that does not noticeably adversely affect the setting properties, in particular the time, such as ground chalk or limestone ·, powdered ash or fly ash and lime; if necessary, a A filler to improve the reflectivity, such as glass (glass ballotini), or a dye or pigment be incorporated.

The mixtures can be applied by the liquid mixture by spraying or other coating sme t testicle is applied. The properties of this basic mixture can be incorporated by incorporation one or more of the materials listed below are modified; each of these promotes that specified basic function; it can add more than

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If

a group used together when their Add properties:

A. additives influencing the rheological properties, such as pumpability of the mixture and behavior in a spray gun during application: calcium lignosulfonate, Cellulose ethers, Vinsol resins (sold by Hercules Powder Co.)> Alginates, polyvinyl alcohol, stearates, etc.

B. Additives, affecting the dimensional stability, which the. Change the shrinkage properties when the base material is dried: zinc oxide, powdered (natural or synthetic) plaster of paris, iron filings or iron dust (preferably through a BSS 200-mesh sieve) _; hard burnt lime, etc.

C. Additives that further reduce gas permeability: e.g. cellulose ether, alginates, polyvinyl alcohol, Stearates, polyethylene glycols, etc.

Closure approach

The same basic mixture is used, whereby, optionally additives of type A, B and C incorporated

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to which a mass is also added to to impart mechanical strength to the cast plug. For this purpose, any material that is available and has adequate mechanical properties, the setting properties the mixture is not adversely affected, e.g. fly ash or pulverized Äsohe, crushed slag, sand ■ fci.es, Limestone, slate, granular blast furnace or other metallurgical slag, etc.

The comprehensive walls of such a plug can ■ conveniently and easily by spraying on a Quick-setting coating mixture on coarse sackcloth or expanded metal -made across the entire cross-section of the tunnel are arranged.

. Example 1 .

Coating mixture based on Portland cement:

D.e.v. 4.0 kg

Mud chalk (whiting, Snocal '.

1 ML-Blue Circle) 7.0 kg

Portland cement (Blue circle) 10.0 kg

Vinsolharz (Hercules Powder Go.) 0 ^, 005 kg Iron filings (in total through a

200-mesh sieve) 0.01 kg

Water about. 2: 1 liter fading time: H- to 6 hours.

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Example 2

Coating mixture based on alumina cement:

D.e.v. 12.7 kg (28 lbs.)

Electric cement (Lafarge Cement Co.) 36.3 kg (80 lbs.) Kieselguhr. ■ 27 ,, 2 kg (6.0 lot)

Water 59 to 73 liters (13 to

l6 gallons)

■ Setting time: 4 to β hours.

These two materials are either in the form of a single layer or preferably for spray application suitable in the form of a multilayer system. This results in better impermeability than that Application of a single thick layer.

. Example 3

Fast-setting mixtures.

These are during the production of walls for Closures, when filling cavities, clogging. Shot holes and with material mixed into them for making closures.

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Such mixtures are obtained quite simply by mixing the materials of Examples 1 and 2 equal parts by weight lead to a very short setting time of 5 to 10 minutes (depending on the on the environmental conditions). The relationship between . the setting time and mixing ratios for cement mixes this type is well documented; compare e.g. T.D. Robson, "High Alumina Cements and Concretes," P. 127 (Constructors Record Ltd, London, 1962).

Further modifications - of these - mixtures can be made getting produced; so is about making one Road bedding (either for a track or for a sidewalk) requires a certain mechanical strength. this can be achieved by incorporating staple fiber glass into the mixture to be sprayed and using it in the system of Example 2 is used. This electrocement system does not devitrify the glass, which therefore reduces its strength maintains. Alternatively, a metal mesh or expanded metal can be used for this purpose.

Other examples of coating or sealing compounds for other uses according to the invention are given below. These can be different

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Have sealing and insulation uses.

Primer coating approach

Dev
Alumina binders

Hydraulic binder

Fillers

Additions. (A, B or C) Addition D.

water

5.4 to 10.9 kg (-12. To 24 lbs.) 0.45 "2.27" '(I to 5 lbs.)

¹¹ 0.454 "(0 to 1 Ib.) ¹¹ 5Λ " (0 to 12 lbs.) ¹¹ 0.454 "(0 to 1 Ib.)

¹¹ 2.72 "(0 to β lbs.) (See below)

suitable to make a sprayable mixture.

The clay binder can be one of the various available clays, e.g. bentonite, kieselguhr, China Clay, powdered montmorillonite, Fuller's earth, nephelite etc.

The hydraulic binder is generally ' only in the outermost layer or in localized places used where some firming up is required; it can be a portland-type cement, an alumina cement, a mixture of these (if quick setting is desirable) or plaster of paris, etc.

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The filler, can be any material that is compatible with the binder system and its setting properties, especially the time, not adversely affected; so it can be ground chalk, ground Limestone, powdered ash or plug ash or the like. be; if necessary, it can be used to improve the reflectivity properties, when it is used as the outermost layer, e.g., Ballotini and further a dye or contain a pigment, if desired.

The properties of this masterbatch can be enhanced by the incorporation of one or more of the following specified materials are modified; Each of these promotes the specified functions:

A. Additives influencing the rheological properties such as pumpability of the mixture and behavior in a spray gun during application: calcium lignosulfonate, Sulphite liquor, cellulose ether, vinsol resins (Hercules Powder Co.)> Alginates, polyvinyl alcohol or stearates,

B. Additives, influencing the dimensional stability, especially the shrinkage properties on drying of the base material: zinc oxide, plaster of paris, iron filings or dust (preferably through a BSS 200-mesh sieve),

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hard burnt lime, etc.. -

C. Additives which reduce the permeability of the mixture to gases, e.g. cellulose ethers, alginates, Polyvinyl alcohols, stearates or polyethylene glycols.

D. Additives to improve the flexibility of the binder system: natural or synthetic chewing agents. school latices, acrylic resins, polyvinyl alcohol and acetate, bitumen emulsion, etc.

In the latter case, care must be taken to ensure that the stabilizers in the latex systems do not impair the properties of the mixture. Since these are also generally present with a solids concentration of about 50 % , less water is required. These are used in the masterbatch noted above in an amount of 0 to 2.72 kg (0 to 6 lbs.) Of added solids; therefore, if a latex contains 40 weight solids, it takes 4.54 kg (10 lbs.) to provide a 1.8l kg (4 lbs.) latex addition.

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• Example 4

Coating for a steel surface requiring a high Is subject to heat movement: e.g. a power plant boiler.

D.e.v. 9 * 3 kg (20.4 lbs.)

Bentonite. 2.0 kg (4.4 lbs.) Sodium carboxymethyl cellulose 0.068 kg (Q ", 15 lbs.) Approximately 45.5 liters (10 gallons) of water

This mixture is applied by spraying, preferably as a multi-layer system.

Example 5

Coating with reduced gas permeability and harder surface properties (finish) '.

D.e.v. "7.94 kg (17.5 lbs.)

Bentonite 0.91 kg (2.0 lbs.)

Whiting agent 5.1 kg (l'l, 25 lbs.)

Sodium carboxymethyl cellulose 0.11 kg (0.25 lbs.) Approximately 4-1 liters (9 gallons) of water.

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If a very thick layer is desired, any of these materials can be applied to a wire mesh or expanded metal or applied to a thin Paserglas base. Alternatively, a certain mechanical strength can be obtained by including staple fiberglass in the mixture.

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Claims (14)

Claims 1. New blend of delaminated flaked vermiculite. 2. Mixture according to claim 1, characterized in that that the mixture has a flake shape, the ratio of the flake width to the flake thickness at least 3ί1. 5 · Method of making delaminated flaked vermiculite, characterized in that flaked vermiculite is treated in a mill, a simple 'shear effect on the peeled Vermiculite particles. 4. The method according to claim 5, characterized in that that a hammer mill is used as a mill. 5. The method according to any one of the preceding claims, characterized in that the leaves on ten vermiculite continuously '"; the mill by means of a Archimedes snail feeds. 909841/1541 ORIGINAL INSPECTED Xt - - se - 6. The method according to any one of the preceding claims, characterized in that the product from the mill is 'on'. Slotted screen removed. · 7 · Method according to claim 6, characterized. draws that a mill with a sieve is used, in which the slots are arranged in a herringbone pattern. 8. sealing or coating mixture, characterized in that it delaminated exfoliated Contains vermiculite together with a suitable binder or binders. 9 · Sealing or coating mixture according to claim 8, characterized in that it also has a Contains filler or fillers. 10. Sealing or coating mixture according to one of the preceding claims, characterized in that that, on average, the largest dimension of the delaminated exfoliated vermiculite particles is 6.35 mm (one quarter inch) or less. 909841/1541 4914323 -ai 11. sealing or coating mixture according to any one of the preceding claims, characterized net that they act as a binder. Contains clay binder. 12. sealing or coating mixture according to any one of the preceding claims, characterized net that it contains a hydraulic binder as a binder. 13. Sealing or coating mixture according to one of the preceding claims, characterized in that that it contains ground chalk, ground limestone, powdered ash, fly ash or lime as a filler. 14. sealing or coating mixture according to one of the preceding claims, characterized in that that it contains a cement of the Portland type, an aluminous cement or gypsum as a binder. ') Π 9 8 h 1/1 5 4 1