DE1583769B1 - Method and device for defibering asbestos - Google Patents

Description

1 2

The invention relates to a method for fiberizing, or else grinders with more or less

of asbestos in the liquid phase, in the case of the one with at least grooved panes.

A hydrocyclone is used to classify fine and die with all the methods known today, coarse suspension, whereby the fine suspension for the treatment of asbestos in the liquid phase is withdrawn and the coarse suspension after a crushing result is more apparent than real grinding is returned to the classification stage . Nature. The asbestos suspensions in the water seem to occur in nature in general in the form of compact corridors in which a large number of very fine fibers have been treated. The individual analysis by granolometrische fibers parallel to each other lying on the results obtained in terms of length and by reason of physical-chemical bond firmly Toggle However knife ¹⁰ showed that in reality on the mutually adhere. These courses are exerted by the rocky fiber by the action only gait by a succession of grinding and very minor nature. It appears that it separated in these separation treatments. In the process, the asbestos process more or less succeeds in making the fibers their compact rock form and takes on a cotton-completely free, which so far partly takes on the similar appearance. In this state he * 5 chopsticks were separated.

delivered to customers. However, this tree is in the known method for defibrating

wool-like asbestos is not yet in its elemental asbestos in the liquid phase is to be treated

Fibers split up, which as crystallites of some asbestos suspensions are first ground and then classified.

Hundredths of a micron in diameter and a length.

of several millimeters, possibly several 20, the diameter of which is actually no longer reduced

Centimeters. The fibers would have to be subjected to the grinding process. this

rather than agglomerated chips, bundles or brings with it the disadvantage that these asbestos fibers

Chopsticks up and surrender, provided that they are reduced in length in this.

Form for the production of paper, cardboard, art- The invention is based on the object

fabrics, textiles or brake linings are used, 25 avoiding the disadvantages indicated above

To create end products with physical or mechanical ability to shred asbestos,

Properties of lower quality. in which the asbestos fibers are separated from each other,

The cotton-like raw material is therefore subjected to it, but not reduced in length,

asbestos an additional treatment that is commonly used to solve this problem is the process according to

Defibering, opening or also disintegration according to the invention, characterized in that the to

is called to treat the chopsticks as finely as possible in asbestos suspension in itself known

To subdivide fibers in such a way that they are fed to the manner before the classifying hydrocyclone

total possible part of the mechanical properties and the coarse suspension withdrawn therefrom

each of the fibers is retained in the final product. For this a disk mill is used to grind. the

Processing come next to Soder processes (Schleu- 35 Suspension is therefore classified first, i.e. it will be

dem, ultrasound, electrical discharges, chemical stripped before grinding those fibers that

Medium) mainly three possibilities in question, namely already reduced to the desired diameter

a treatment in dryer, wetter or liquid. Their length will therefore be preserved, and will be

Phase. only those components of a grinding

A treatment in the dry phase always results in 4 ° thrown as coarse material from the hydrocyclone

a mechanical treatment in which the fibers emerge. One obtains with the desired diameter

bundles or sticks crumble and grind fibers of optimal length.

will. A major disadvantage is that it is known to use a hydrocyclone

Upstream bundles not only in diameter, but also grinder, but this is not possible

can be reduced in length. The individual 45 about the processing of asbestos fibers, the diameter of which

So fibers are broken. It is true that knives are used while the length remains the same

also less hard-working percussion mechanisms, however, are supposed to.

these are also less effective and must therefore be used. The method according to the invention is quite suitable

a plurality are connected in series. general for the treatment of asbestos, such as

Treatment in the wet phase leaves a 5 "white amphibole asbestos. In particular, it is on

Assessment of the fibers obtained according to the diameter of chrysotile-asbestos can be used. Especially this asbestos

and length not too, as the individual chopsticks in will be known to be considerably less brittle when

Tufts are transformed, the fibers of which are present in a water, compared with the dry

End are still firmly connected. A state of asbestos. In fact, this one has

Such a treatment had to result in a hollow structure in asbestos (according to the literature, a

disadvantageously still a complementary empty or filled with a silica gel on construction).

Connect processing. The hollow fiber tries to fill up with water.

With the known treatments suck in the liquid phase, which significantly increases their flexibility,

Finally, the asbestos is more or less in spite of the mediocre, so far due to this

Diluted water put in suspension, the results obtained by those interested in the problem

Asbestos concentrations in water in general is now an effective industrial one according to the invention

between 5 and 20 ° / ₀ . One uses either treatment to separate as finely as possible

a cone refiner of the type that succeeded in asbestos fibers while maintaining their length.

Paper industry application or from there is preferably in the process according to the

are at least derived and in which sometimes 65 invention the asbestos content of the to be treated

certain metal parts are replaced by elastic elements asbestos suspension below 10 grams per liter of water,

be, or a snake tube or an eccentric while the fine and coarse suspension about 2 grams

drum causing torsional and friction effects or less than 50 grams of asbestos per liter of water

I 583 769

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and the pressure in the circuit some bar weaker concentrations, which are always below

amounts to. 5 percent by weight. The result is unexpected.

According to the Er- Man now has chopsticks, which are all the easier to move into

the lower the concentration, the lower the concentration, the lower the concentration

described method created, which is thereby 5 tration; the most effective work is obtained for

is characterized in that the grinding disks of the disk concentrations below 5 ° / ₀ . The more fibers full

If the mill is made of stone or a similar material, if water is sucked in, the quicker it can be done

the distance between these disks being treated smaller, and the less you damage them, the more

than 0.1 mm. less one reduces their length.

Method and device according to the invention io Incidentally, it is in the treatment industry work with elements known per se, but very well known for minerals, for example hydrocyclones abnormal working conditions. wise to the separation of in suspension in water

This is because it is known per se to apply powders to disk mills as a function of their density to separate small asbestos fibers for dry fiber removal (e.g. to remove metallic minerals from use. There is, however, an essential difference in separating their gait as a function of their parting to the invention. measurement (thicker or thinner grains) or as

In the case of this drying process, the grinding functions are their shape (separation of the mica and

disks fluted or ribbed, and the both of grains of sand).

The distance between grinding disks is often in milli- It is also known to use fiber in hydrocyclones

meter order of magnitude, while according to the invention to treat 20-shaped materials; so-called travel

Space between the disks as small as possible are used extensively for the niger cyclones

and is preferably smaller than ¹ I ₁₀ mm. Used on every paper industry to make the cellulose fibers

Case can only very short fibers dry in slices from the various starting grains that they

Mills are treated as the reduction of the contaminants can separate (for example sand).

Chopsticks made into fine fibers by attrition; this 25 It is also a case of using hydro-

but brings a significant reduction in the length of cyclones for separating asbestos fibers as a function

and a very noticeable increase in the dust content of its length has become known, it is here

of the fibers with it. This dust is nothing but a case where the long fibers for the

other than fibers that have been reduced to powder. markedly disrupt intended purpose; she

If, on the other hand, the inventive method 30 must be eliminated and reduced

if a disk mill is used, its length can be traced back to a grinder,

effectively treat asbestos of any length without using the hydrocyclone

to damage them noticeably, as the following ones, according to the opposite purpose. Inventive

show result tables. accordingly it was found that if one

It is therefore important, and completely surprising, to place an asphalt fiber in a suitable hydrocyclone.

that the disks of the disk mill initiates a suspension, the latter not in function of it

stood y equal to zero and yet the asbestos length, but as a function of its length / diameter

do not grind, but defibrate. If it was a question of proportion to be classified, it follows that one

to a substance other than asbestos or would use the hydrocyclones to classify asbestos as

Mill used for asbestos in dry form, so 4 ° function of length for a given diameter

would be able to use this fabric or this dry asbestos with (this is the case of the known above

a zero clearance between the grinding disks zer- described use) or as a function of the

grind, d. H. reduced to dust. In the liquid phase of diameter for a given length; this is the

on the other hand, according to the invention, the asbestos does not decay, which is to be exploited according to the invention,

grind, not reduced to dust, but defibred.45 According to the invention, it became evident that

d. H. separated or isolated into fine fibers. the hydrocyclone and the disk mill in

It is also known to connect disk mills in a liquid series, a combination of two treatment

Phase not to use the fibers as they reach the lungs, which complement each other and the

are to be treated in some way, but to adapt well to each other, as the hydrocyclone

To grind more or less fragile bodies 5o has the task of the aqueous asbestos-cement suspension

and to convert suspensions into emulsions. concentrate and add this suspension to the mill

In all cases, the weight concentration is the desired concentration to be added so

tration of the solid materials in the liquid run the mill under the best working conditions

at least 5%, often 10 to 20%. The chosen works.

Concentrations represent the result of a compromise. For example, embodiments of the invention

misses between the fluidity of the suspension and will now be explained in more detail with reference to the drawings

the efficiency of the mill. There is now one in which

Interest in the lower limit of fluidity to F i g. 1 schematically shows an overall arrangement according to FIG

work in which still shows an easy passage of the invention;

Suspension through the mill is possible, which results in ⁵ ° F i g. 2 is a diagram and shows the important, on the one hand, the amount of this limited by the device gain in resistance of asbestos-cement flowing suspension and thus its products, which contain asbestos, which is increased in an efficiency and on the other hand, the pilot-controlled disk mill according to the invention escapes the Recuperation of the liquid phase is to be kept, compared to products that contain asbestos Elimination of the liquid phase cheaper to 65, which is designed by grinding or squeezing works, whereby the amount of liquid phase was then obtained using the known methods,
also gets lower. After the in F i g. 1 illustrated embodiment. According to the invention, one now works when the invention is essentially based on a treatment cycle

5 6

an aqueous asbestos suspension applied. In pointed fibers are to the inlet funnel 19 of the an aqueous asbestos suspension 2 disk mill 18 is fed to a boiler 1. In this disk mill contain their dilution, d. H. The fibers that are soaked in water suffer from the proportion of asbestos that surrounds them Relative to water to a certain value one have a great flexibility, the passage is posed. 5 between the discs 20 and 21 without being broken

In the boiler 1 occurs at 3 fresh food that has not been defibrated.

asbestos (as it is obtained from the pit), when they are only separated from each other, and when

4 clear or new water, at 5 recuperation water, it from the disk mill 18 through the discharge for example, exit from the interior of a sieve of a pipe 22 in order to be dispensed into the vat 1 Board machine comes, assuming that to be ok, they are in large part in Elementarder Asbestos is to be processed into foils. In the fibers, d. H. very fine fibers, separated or isolated, Schematic representation is only a sieve 6 The fine separated by the hydrocyclones 12

shown that in one of the asbestos suspension 8 containing fibers emerging through the upper ducts 14, the kettle or vat 7 is immersed. are through the collecting line 15 to their distribution

From the lower part of the boiler 1 a line 9 goes to 15 turning point, i. H. in the present case from which the aqueous asbestos suspension from a pump 10 to the tub 7 of a cardboard machine, which is used as a centrifuge. This pump pushes the suspension through or the squeezing machine works and the asbestos in a line 11 against a battery of hydrocyclones film form, which is stacked before its use 12 connected in parallel. The aqueous one that is supposed to become supplies. The fine fibers can, however Asbestos suspension derived from line 11 enters the 20 as well as being used directly by it Hydrocyclones 12 through tangential inlet nozzles 13 in, for example, in a vat to prepare a near the top of the hydrocyclone. Asbestos-cement headbox. In advance the upper part of the hydrocyclones 12 are the fine, in the tub 7 in Above lines 14, so-called overflow lines made of asbestos fibers in suspension onto the sieve 6 which are connected to a manifold 15, deposited 25, from where they are in film form on a soft the suspension is discharged from isolated fibers, felt, not shown, are transferred, in the present case they the boiler or vat 7 According to the invention it was found that, to a

feeds the board machine when the asbestos is to be processed to a good classification of the fibers according to the length of the foils. Diameter ratio in the hydrocyclones to From the lower part of the hydrocyclones 12 enter 30, the asbestos concentration in the aqueous, in lower lines 16, so-called underflow nozzles. the hydrocyclones 12 treated suspensions The lines 16 are connected to a collecting line 17 between 5 and 10 grams per liter, connected in parallel, which contains the asbestos to be treated. Diameter ratio. Grinding disks feeds, the axis of which is indicated at XX 35 Since the hydrocyclones 12 is also in terms of thickness. exert an effect, the concentration of the asbestos suspension increases noticeably. It can have a value that has an annular fixed disk 20 (stator) and a disk21 (rotor) cruising between six and ten times the initial rate, soft 40 concentration in front of the hydrocyclones, ie in the line 11 rotating by a motor (not shown), accept. One reaches so in unawares. According to the invention, the play / between teter concentrations in the vicinity of the optimal concentration desired by the disks 20 and 21 is as small as possible and the disk mill is practically zero. The disk mill 18 finally carries tration.

a discharge pipe 22 on the circumference, which is the treated 45. According to the invention, therefore, good results are made from suspension Pour into the kettle 1 and to the going from an aqueous suspension in kettle 1 classifying hydrocyclones 12 recirculates. and a minimum concentration of 5 grams

The mode of operation is as follows: With the help of asbestos per liter of water, get. That is how you achieve described device one proceeds as follows: a slurry, which from the lower subflow lines 16 The vat 1 is at 3, 4 and 5 each with raw 50 with a concentration on the order of asbestos, "new" water and recuperation water, 30 to 50 grams of asbestos per liter leaks, in which asbestos fines are contained, in those which emerge from the upper overflow pipes 14

Quantities fed so that the pulp of the invention or the slurry is treated as finished according to the highest possible dilution. viewed and may have to be thickened

The metered suspension enters the line 9, 55. She possesses a concentration in the size asserted the pump 10 which it in the line 11 to order 2 grams of asbestos per liter. The one Hydrocyclones 12 pushes. The hydrocyclones most skilled and most effective method of thickening work so that in order to get tangential this suspension consists in the loading enema the asbestos suspension with a certain amount of action on the sieves 6 of a cardboard machine. Pressure and at a certain speed at 6 ° This suspension is used to make an asbestos sheet the suspension is divided into main streams to produce which are therefore used directly which one can spiral like a vortex to the lower by keeping them in suspension in liquid phase Underflow lines 16 migrates and down the back transferred.

agglomerated fibers takes with it, the other one can also use the asbestos suspension with a

spiral against the upper overflow lines 14 65 filter press or any other filter (vacuum in rises and takes the fine fibers with it. drum, flat shape, etc.) thicken.

The thick or agglomerated, used by the hydro For the optimum efficiency of defibering

cyclones 12 via the lower lines 16 disconnection device, d. H. the disk mill 18, it must

Play / between the disks 20 and 21 must be minimal. That is why the disks 20 and 21 are also practical in contact with each other.

The numerical values listed below in the various Tables I to VII give results and advantages of the invention compared with the results obtained by known methods recognize.

1. Table I below shows the grain size ratios in terms of the diameters of some commercial asbestos, as they are delivered by the mining companies.

Table I.

Determination of grain size in the diameters of some commercially available asbestos

Number of fibers Canal Rhodesian Canal (in%) with a through
knife-smaller than QlSCiie;
quality
IV Chrysotile,
. Quality V discne
quality
VI 10 microns 2 2 2 20 microns 3 3 3 50 microns 11th 14th 16 100 microns 44 60 66 200 microns 98 99.2 99 % Fibers with a diameter greater than 200 microns 2 0.8 1 Diameter of the middle one Fiber ¹ ) in microns 105 . 91 86 ■

*) Fiber diameter such that 50% of the fibers are thicker.

50% of the fibers finer,

These grain size determinations with regard to the diameter are made by examination and optical Counting determined.

Table I shows the cumulative percentages of fiber diameters increasing to 200 microns; the proportion of fibers with a diameter of less than 20 microns, which is 3% of the first column, corresponds to the proportion of fibers with a diameter of less than 10 microns of 2%; that of fibers with a diameter between 10 and 20 microns is 1%; this number is not entered. On the other hand, the proportion of the thickest fibers, that is, those whose diameter is greater than 200 microns, is obtained by the difference between the number 100 and the preceding cumulative proportion, such that the total of the two rows (98 + 2), (99.2 + 0.8) is equal to 100. ^;

The following Table II shows the grain size distribution in terms of the length of a Canadian Asbestos of the quality that has been treated according to various known defibering processes (Dry crushing or grinding, hammer crusher, with one or more passes in the crusher, Moist grinder + Holländer, 'rod grinder in liquid phase, Hydfodesintegratiotasvorrichtung with Discs and ultrasonic methods) such as the method according to the invention.

Table II

Grain size distribution along the length according to the type of defiber removal carried out by sieving

on a Canadian grade IV asbestos

⁰ U fibers
longer than?) Pit
Raw
asbestos Dry
grind
(30 min
ten) 1 round
through a
Hammer-
crusher Possible
Optimal through
Treatment in
a hammer
crusher Grinding in
wet phase
50% water
+ Dutch Rod
crusher in
wet phase
50% water Hydrodes
integration
contraption
with washers
working Ultra
sound Invent
manure 2.4 mm
1.2mm ......
0.6 mm
0.3 mm
0.08 mm
° / ₀ fibers with
with a
Length smaller
than 0.08 mm .. 5
23
47
61
67
33 0
10
27
40
47
53 5
23
46
60
66
34 5
23
45
57
63
37 4th
22nd
43
56
61
39 5
23
45
56
62
38 5
23
47
58
65
35 5
23
47
61
67
33 5
23
46
58
63
37

Lengths determined by sieving in the liquid phase.

109 540/176

These granulometric length measurements were made by liquid screening in a row made by stacked sieves that are becoming finer and finer.

As shown in Table I, these results express the cumulative percentages that the fibers decrease with Lengths from a value greater than 2.4 mm to a length at least equal to 0.08 mm prevail one after the other the various sieves up to the penultimate sieve. In contrast, the percentage of that Fibers penetrating fine sieve, d. H. the percentage of fibers whose length is too short to measured by the difference to 100 of the previous cumulative fraction. In the first column, for example, the proportion of fibers that are longer than 2.4 mm is 5%;

10

the proportion of fibers longer than 1.2 mm includes those fibers which are longer than 2.4 mm and those whose length is between 1.2 and 2.4 mm; the number (23%) is therefore equal to the cumulative proportion of fibers that are longer than 2.4 mm (5 ° / ₀ ), the proportion of fibers with a length between 1.2 and 2.4 mm is 18% - this number is not entered - etc. up to the penultimate line of the table.

It is now found that, in addition to the dry 30-minute grinding or crushing process, the im Substantial less good results will result from the various procedures including after the Invention to maintain the length of the fibers.

3. Reference should now be made to Table III which shows the grain size dimensions of the diameters according to the nature of the defibering.

Table III
Granulometry in diameters according to the defibering

Attack of fibers Raw Dry 1 round Possible
Optimal through Squeezing in Poles Hydrodes Ultra Invent (in%) with a asbestos to squeeze through a jöenancuung im wet phase grinder in integration sound manure diameter from the (30 min Hammer- tiarflmer-
crusher 50% water wet phase by less than pit ten) crusher 2 + Dutch 50% water Discs 2 19th 2 microns. 1 1 1 3 2 2 1.5 2.5 61 5 microns. 1.5 2 1.6 8th 3 3 2 3 99.2 10 microns. 2 2.5 2 32 7th 6.5 2.5 8th 100 20 microns. 3 5.5 4.5 99 31 30th 4.5 55 50 microns. 11th 29 25th 99.4 98 97 23 99.1 _ 100 microns. 44 91 83 99.9 99 99 76 99.8 - 200 microns. 98 99.4 99.2 99.8 99.6 98 % Fibers with one through knife bigger 0.1 0.2 0 than 200 microns 2 0.6 0.8 0.2 0.4 2 diameter 25th 48 4.5 in microns ¹ ) .. 106 64 71 27 28 77

*) Fiber diameter such that 50% of the fibers are finer and 50% thicker.

Comparing the number of small-diameter fibers and the diameter of the medium-sized ones Fibers of the treated asbestos - assumed to be known - with the corresponding values of Asbestos treated according to the invention, it is found that only in the process according to the invention an actual defibering is present, since in the asbestos treated according to the invention on the one hand the The proportion of fine fibers is significantly higher and, on the other hand, the diameter of the middle fibers the asbestos is 5 to 17 times smaller than fibers from plants of the known type. if in addition, the diameter of the mean, derived from the process according to the invention Compares fiber (4.5 microns) with that of commercial asbestos, raw pit asbestos (106 microns), it is seen that the diameter of the fiber obtained is 20 times smaller.

4. With fibers of Canadian origin, quality IV, which had been subjected to the various known treatments, but also to the treatment according to the invention, asbestos-cement panels were made. These panels are made by mixing 10% fibers with 90% portland cement, type CPA 400, by immersing 150 grams of this mixture in ^x / a liter of water for 2 minutes with stirring; this paste is then poured into a mold with a perforated bottom, which is lined with filter paper and subjected to a vacuum of 40 cm of mercury.

At the end of the squeezing or spinning under vacuum, the plate produced is subjected to a compression of 100 bar, then ^{"matured" in a chamber at 20 °} C. and 100% relative humidity for 14 days. At the end of this ripening process, the panels are broken by bending them on a test press. The results so produced are similar to those given in Table IV below.

11 12

Table IV The resistance imparted by the fiber to an asbestos-cement mixture after the asbestos has been defibrated

daN / cm ² Koner
Pits
asbestos Dry
squeeze 1 through Optimal
possible Squeeze
or grinding Poles
grinder Hydrodes Ultra-,
sound Invent
manure or
Grind
(30 min
ten) corridor
through a
hammer
crusher treatment
through a
hammer
crusher in damp
Phase,
50% water
+ Dutch in damp
Phase,
50%
water integrator
with
Discs
working More specific g / cm ³ resistance 229 234 312 against bending 241 231 259 252 245 235 Apparent daN / cm ² 1.86 1.67 1.67 density 1.78 1.75 1.70 1.68 1.67 1.76 More specific resistance 170 215 287 at d the same .. 195 193 230 228 225 194

Asbestos cement formed from: 10% asbestos, 90% Portland cement type CPA 400 Maturation: 14 days (20 ⁰ C, 100% relative humidity).

This table accurately confirms the observations made in Tables II and III and shows the clear Superiority of the method according to the invention over the known methods. The specific as Resistance to deflection of the sheets of fine fibers obtained by the inventive Process obtained is much larger than that of panels made from thicker fibers which were supplied by the known methods.

5. The invention is now applied to a chrysotile asbestos, quality V, Rhodesian origin, the to be designated with A, as well as on a chrysotile asbestos of quality VI, of Canadian origin, the to be denoted by C.

Concentration of the suspension: 2 to 5 grams per liter of water.

Device: pump 10 which presses the suspension into line 11 under a pressure of 1 to 3 bar.

4 hydrocyclones 12 of the type DORR-OLIVER T 204 II.

Rolling mill 18 of the ULTRAMILL type, type UM-22, which is driven by a 15 HP (15 CV) motor Grinding stone 21 rotates at 300 revolutions per minute, with the play / between the Grinding or grinding stones 20 and 21 is smaller than 0.1 mm.

The asbestos emerging from the upper lines 14 of the hydrocyclones 12 has a concentration of 2 grams per liter, while the asbestos emerging from the lower lines 16 is a concentration of 45 grams per liter.

Granulometric measurements on fibers that have been sent once through a pan mill 18, were carried out by sieving in the liquid route. These measurements are continued in Table V. reproduced below, in which the granulometry of raw asbestos with regard to its length with raw asbestos and compares it with asbestos in the pan mill in the liquid phase without a hydrocyclone were treated.

Table V Comparison of the length granulometry

% Fibers longer than ¹ )

A — Rhodesian asbestos, quality V

After a pass through Vor of a pan grinder without Hy treatment drozyklon (zero between the millstones) C - Canadian asbestos, quality VI

After one pass in the
In front of the pan mill without hydro-treatment cyclone (between the grinding stones zero)

2.4 mm

1.2 mm

0.6 mm

0.3 mm

0.08 mm

% Fibers shorter than
0.08 mm

18 40 62 70

13 36 57 66

34 0
1
8th

25th
40

60

19th

34

36

^x ) length determined by sieving in the liquid phase.

This table shows that in the treatment of the invention, the length of the fibers is approximately maintained because the percentages of the longest fibers are roughly retained.

6. Table VI shows a comparison of the length granulometry after complete treatment of the invention, d. H. after using the classifying hydrocyclones according to the diameter ratio from length to diameter, showing the even more improved results, being the percentages of long fibers compared with the previous case, even closer to those prior to treatment, which underscores the usefulness of the classifying hydrocyclones.

13th

Table VI Comparison of the length granulometry

14th

% Fibers, longer than

A - Rhodesian asbestos, quality V

Before treatment After treatment in the hydrocyclone - pan grinder arrangement (according to the
Drawing, zero between the millstones)

C - Canadian asbestos, grade VI

Before the
treatment

After treatment in the arrangement hydrocyclone - pan grinder (see fig. between the millstones zero)

2.4 mm

1.2 mm

0.6 mm

0.3 mm

0.08 mm: ",

% Fibers shorter than
0.08 mm

f .;

18 40 62 70

30th

2 18 39 56 64

36

1
8th

25th
40

60

12th
21
37

63

There is therefore no shortening of the fibers. The long fibers, which have a substantial length to diameter ratio and exit through the upper overflow conduits 14, are not broken. Single Lieh fibers having a low ratio of 'length to diameter (this is the case for the majority of the fibers having a length less than ⁶ I ₁₀ mm) are treated in the mill 18, which is a very slight shortening of the bottom of the lines 16 exiting fibers.

7. A comparison equal to the ·., Resilience the asbestos cement panels using the invention treated fibers versus those treated by known methods Fibers were used shows an improvement in resistance in the order of magnitude 30% in favor of the technique proposed according to the invention, as shown in the following comparative table VII of FIG shows mechanical properties of asbestos cement panels.

Table VII
Properties of the asbestos cement sample panels

ί.

Asbestos ratio asbestos and cement ¹ ) A - Rhodesian asbestos, quality V
. 10%

MH

invention

profit

invention

profit

MH

12%

invention

profit

Specific resistance daN / cm ² ..

Density of the "end product

Specific resistance at constant density (= 1.6) daN / cm ² .. Resilience kg ■ cm / cm ² ..

228 _. 17%

182 2.2

JTO

250 3.0

37 36 254
1.76

210
2.7

345
1.74

291
3.3

38
22nd

261
1.75

223
3.0

355
1.70

297
3.6

Table VII continued

".. asbestos ratio" asbestos and cement ¹ ) '

ί. * Invent
manure " Canadian Asbestos - C - Grade VI MH 10% Ge
winn
% .-MH 12% I.
i
1 242 186 Invent
manure 207 Invent
manure MH - 1.77 Ge
-winn
% 1.79 271 1.74 284 175 | 198 - 152 1.76 47 175 1.74 1.82 2.0 1.5 223 33 2.3 240 135 47 2.0 2.8 1.5 33

Specific resistance daN / cm ² ..

Density of the end product

Specific resistance at constant density (= 1.6) daN / cm ² .. Resilience kg · cm / cm ² ...

^x ) MH = results obtained by classic industrial treatment in a moist squeezer with a downstream Hollander. ² ) Binder = Portland cement, matured for 14 days at 20 ° C and 100% relative humidity.

The table shows a slight decrease in density of the plates containing fibers treated according to the invention compared with those according to known Process contained treated fibers, as well as a clear improvement in resilience, wherein the profit can exceed 20% following the treatment according to the invention. This improvement the resilience of the finished products has an unexpected effect. It's on it to point out that the same resistances are obtained for Rhodesian asbestos with the treatment according to the invention of the plates as with the usual treatment

Claims (1)

15 16 obtained when the proportion of asbestos is more effective and the homogeneity from the top is greater than 4% Jm absolute value and more than 30% in the overflow lines 14 exiting fibers. relative value decreased. The treatment after c) finally allows the treatment in liquid Invention allows a considerable saving in phase and classification into a non-defibered one Asbestos. 5 a defibered part with the help of hydrocyclones 12, The graph according to FIG. 2, in which during this classification on the dry route on the abscissa the play j (expressed in mm) is impossible. The use of hydrocyclones between the millstones 20 and 21 and on top of it therefore allows a greater homogeneity of the fibers Ordinate of the specific resistance RC (to be obtained at kon-. constant density) in daN / cm ² of those with the same io The first advantage allows asbestos losses in the form Asbestos cement panels manufactured on parameters to avoid dust, which in addition to the is worn and contaminated, especially if the asbestos atmosphere is constant. ratio, shows the significant increase in the cons The second advantage allows the elimination of the Stand of an asbestos cement board, made up of principal failure of the usual treatments, the of fibers consisting of upper overflow lines 14 15 that is insufficiently defibrated and in originate, compared to the finished products made up of fibers, numerous sticks or shavings left behind by the usual procedure and by excessively dampening the length The squeezing mechanism is completed by a shortened one. Dutch refiner were treated. In the gra- The latter benefit is the most important. By phical representation of the full-line 20 the classification show in an open or defibrated curves A and C, the characteristics of asbestos and an open and non-defibered part vernach the inventive treatment and one avoids that all fibers uniformly geLinien A 'C intermittently Representation of the maximum must be milled, which would mean that paint properties of the asbestos according to the classical both the thickest sticks, the several tenths of treatment. Can reach 25 millimeters in diameter as well Curve A ' refers to Rhodesian chryso- the fine fibers that do not require a grinder tilasbestos of quality V: is, would have to be ground. One also avoids The medium strength of the asbestos-cement sheets causes a break in the fine fibers. In addition (classic treatment) is much smaller than this classification allows fine asbestos fibers of a 250 daN / cm ² , while for the panels after the 30 greater homogeneity is obtained and thus pro or carried out with only one grinding stone) which is of a quality that is equal to that of the known speaking value (curve A), considerably above products, which results in a considerable host-250 daN / cm ² . economic efficiency of asbestos results. Curve C ″ relates to a Canadian 35. However, the invention is not related to that shown Asbestos of quality VI, after classic treatment and described embodiment, limited that only in the damp squeezer and in the Dutch refiner: for example, was given. The strength of the plates is significantly below. So the separation or insulation can be improved 250 daN / cm ² , while after the treatment in the can be by removing the fibers from the upper lei pan mill, the grinding stones with a 40 l4 and lower duct 16 the hydro little game y were set between them, in cyclones 12 in other hydrocyclones that are connected to the liquid phase according to the invention (curve C) of these collecting lines 15 and 17, be value is significantly higher than 200 daN / cm ² . The acts. Graphic representations show that the noticeable So the fibers treated in this way can also be used to increase the resistance for a game j between the grinding stones 20 and 21, which are used as little as possible and for the production of different ones as possible , is preferably zero. As soon as this product, for example of insulation products, pa clearance increases, there is an improvement over the pieren, filters, etc.
normal treatment no longer detectable. In summary, one can say that the Stones 50 struggled by the treatment according to the invention claims:
compared to the usual industrial treatment
to 40% in strength and about 20% in terms of strength of the suspension capacity. 1. Process for shredding asbestos in The liquid phase obtained by the process according to the invention, in which with at least one The advantages are threefold: Hydrocyclone classification into fine and coarse a) The moist treatment removes the suspension, which is harmful to the fine suspension Dust in the atmosphere is drawn into itself and the coarse suspension according to a well-known Way. Grinding returned to the classification stage b) The defibering is significantly improved, is characterized in that by taking advantage of the fact that the chrysotile is the asbestos suspension to be treated in itself Fibers are in the form of tubes, as they are spiral-shaped, as is known, before the classifying hydroforming are wound up and have a tendency to be fed to the cyclone (12) and from it Soak up water, which makes them more pliable and drawn coarse suspension with the help of a disk less brittle. You can therefore use a mill (18) to grind them. much rougher treatment can be granted, 2. The method according to claim 1, characterized in that without having to shorten them in length. draws that the asbestos content of the to be treated It follows that the defibering treatment asbestos suspension is below 10 g per liter of water is, while the fine and coarse suspension about 2 g or; contain less than 50 g of asbestos per liter of water and the pressure in the circuit is a few bar.
3. Device for carrying out the method according to one of the claims. 1 or 2, characterized in that the grinding disks (20, 21) of the Disk mill (18) made of stone or similar material, the distance between these disks is smaller than 0.1 mm. 1 sheet of drawings