DE2912326C2 - Wet dust control method - Google Patents

Description

The invention relates to a method for wet dust control in which the dust binding capacity of water is increased by chemical additives.

The invention is used in branches of industry where dust is generated during work processes or where there is a risk of dust generation, in particular it is used to combat wet dust and silicosis in coal mining, ore mining, in the potash industry, in the field of "construction, stones, earth" and areas who are faced with comparable room problems. Significant advantages have also been achieved in connection with the various impregnation processes in mining and with sprinkling and sprinkling in the mechanical extraction of minerals.

Dust control measures in mining today make a significant contribution to humanization of the job and thus also the retention of jobs. Deposited in the alveoli of the lungs Dust that can no longer be removed from the lungs is the cause of the occurrence of Pneumoconiosis or silicosis (dust lung), one notifiable occupational disease that is subject to compensation, from which around 1000 People in the Federal Republic of Germany fall ill. You know through medical examinations today that only a part of the inhaled dust, namely the smallest particles of quartz dust of one particle size below 10 μπι, deposited in the alveoli that Impaired function of the respiratory organs and lead to severe secondary circulatory disorders and ultimately lead to premature death.

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Mining machines and belt transfers as well as coal impact impregnation from the dust or the routes a. In order to increase the dust binding capacity of the water, the use of additives is already necessary on the basis of surfactants (wetting agents) or calcium chloride have been proposed (R Seewald, J. Klein, H. Bremer, H. Jüntgen, “Investigations on the Wetting properties of dusts and about the optimal application of suitable additives for the

ίο Improving dust control with water ", Silicosis report North Rhine-Westphalia Volume 11/1977, Glückauf-Verlag; M. Reinhardt "Innovations at the Dust Control Exhibition of the National Coal Board", Glückauf-Verlag, Glückauf 21/1974; HD Bauer, H. G.

iä Klinker, »The effectiveness of surface-active substances during wet dust control on shearer loaders «, Glückauf-Verlag, Glückauf 5/1971).

In the journal Bergbau 7/1978, pp. 313-319, studies to increase the effectiveness of the spray water used on the shearer loaders using non-ionic wetting agents such as polyalkoxylated nonylphenols or calcium chloride are reported according to the method of DE-AS 12 45 909 Nonionic wetting agents, namely water-insoluble alkylene oxide additive products to compounds containing lipophilic residues, are used as binders in the removal of solid or liquid suspended particles from air and gases in gas cleaning systems, which result in aqueous solutions which do not foam or which foam only slightly and which result from these solutions in oily form deposit. For dust control, DE-PS 8 04 203 proposes the use of aqueous solutions of alkylarylsulfonates with side chains containing at least 10 carbon atoms and of hygroscopic alcohols, while according to DE-PS 809 663 mixtures of other wetting agents with polyhydric hygroscopic alcohols are used. Arylalkylsulfonates are compounds with the typical structure of a hydrophilic and a lipophilic radical, as characterizes numerous surfactants . <. _n n _A " _an .. ,,. ,, 4 ^ _n / i ic, dc ~> i 95 573 ^

The use of wetting agents and other agents with a surfactant-like structure as well as calcium chloride leads to a dust reduction of around 15 to 30% in the impact impregnation. The use of the well-known Spray additives are still very controversial. Because of its corrosive behavior is here the use of calcium chloride is not possible; very contradicting results are obtained with surfactants which do not allow any reliable statements about its effectiveness. This will affect both the

Pit is also an important factor in preventing dust explosions that occur in underground areas caused by the whirling up and ignition of deposited dust.

Dust control measures in mining therefore aim to improve operational safety Protect miners' health and reduce secondary silicosis costs.

Dust gets underground in different situations and areas with different technologies fights. Wet dust control with water by spraying takes on an important place here given degradation conditions as well as different reactions of the wetting agents to the different Geological properties traced back The use of wetting agents also comes across hygiene concerns, as the surfactants can get into the lungs and in this way even the transport existing dust deeper into the lungs. Although with the methods proposed so far some limited success has been achieved in wet dust control with chemical additives is in view of the operational safety and security problems caused by dust

Health of the working people threatened by dust a further reduction of the dust among the different operating conditions.

According to the method of DE-PS 9 43 666, dust is moistened with aqueous solutions of monomeric acrylamide and optionally wetting agents, the dust particles being coated by the solutions and completely uncontrollable and undefined polymer molecules being formed in situ. A crosslinking of dust suspensoids by adsorption forces does not take place and the latices ^ °? also with the help of a precipitant v -. <; NaCl, aluminum sulfate alcohols or acids ko ³ 5HÜert The physical precipitation of the latex that takes place in the process also leads to a certain coating of the dust particles

The object of the invention is. d't Provision of a method for combating dust by wet means using chemical additives, with which a reduction in the dust concentration beyond the dust reduction achievable up to now can be achieved or the formation of dust is reduced to a minimum or completely prevented. Such a process should work with chemical additives that are neither aggressive nor corrosive and also work perfectly under hygienic conditions.

This method should preferably make use of simple metering of the additive. It the aim is to combat dust which is particularly high in the case of dust containing silicate Effectiveness unfolds through constant activity and in this way a dust control with constant reproducibility Mining, with such a process, can be improved, iniem the risk of dust explosions is reduced.

To solve this task * the invention proposes the Ve * drive specified in claim 1 to the wet Dust control using chemical additives. Claims 2 and 3 have preferred refinements of this method are the subject matter.

“Acrylic” here refers to both the group

CH ₂ = CH-CO

as well as methacrylic and other lower alkacrylic homologs.

As a result of the method of the invention, a comparison with additives previously used is essential more effective dust control on the said

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Compounds lead to a favorable agglomeration of the dust particles and bind when they are in water Phase are supplied, surprisingly more solid particles with the formation of larger particles, whereby the pulmonary accessibility of such dust aggregates is greatly reduced. As a result, through Application of the proposed method, e.g. B. in coal mining for coal impregnation and / or when spraying and sprinkling the belt transfers and conveyor systems caused by dust particles Risk of explosion greatly reduced or completely eliminated The method of the invention ensures but also a more effective and better use of the sprayed water by reducing the abandoned water mist.

Cationically modified acrylamide polymers and acrylamide polymers obtained by copolymerization from 5 to 95% by weight of acrylamide with 95 to 5% by weight of one or more comonomers from the group of Acrylate monomers have been found to be proved particularly beneficial.

This applies in particular to acrylic acid-acrylic acid amide copolymers, in which about 10 to 80 wt .-% acrylic acid units and about 90 to 20 % By weight of acrylic acid amide units, based on the sum of the monomer units in the polymer, the acid nips optionally with an alkali, alkaline earth, ammonium and / or amine base neutralized and / or optionally acrylic acid amide groups are cationically modified.

Suitable acrylamide polymers have one or more units of the in their polymer chain general formula

R.

C-C-

R ₂ C =

R ₄

in which, independently of one another, the radicals Ri, R ₂ and R3 are hydrogen or lower alkyl groups with 1 to 4 carbon atoms, R ₄ and R5 are hydrogen, lower alkyl groups with 1 to 4 carbon atoms or groups of the form!

-CH ₂ NR ₆ R ₇

are, wherein R «and Rr are hydrogen and / or lower Represent alkyl groups having 1 to 4 carbon atoms. The lower alkyl groups can be straight-chain or be branched. They are polymers or copolymers that contain one or more monomer units of the formula given contain, optionally together with other monomer units, the may optionally be electrolytically "inert". Their molecular weight is preferably in the range of 100,000-10 million, with molecular weights above about 1 million being preferred.

Particularly suitable acrylamide polymers are homopolymers of acrylamide, which may be

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how secondary amines may have been modified, and copolymers produced by interpolymerization of \ crylamid with one or more comonomers from the group of acrylamide and / or acrylic monomers. she can with a smaller amount, mostly less than 50 mol% of the total monomer units, one "Inert" ethylenically unsaturated monomers be copolymerized, as long as their solubility in water or This does not affect the dispersibility in water too much.

A group of suitable cationic and anionic Polyelectrclyte is in DE-AS 21 54 081 and DE-OS 22 26143 described.

Another class of chemical additives are polyamines which have secondary, tertiary or quaternary amino groups in a macromolecular matrix which are bonded in essentially linear polymers via alkylene, cycloalkylene, arylene or aralkylene groups. Particularly suitable polyamines include polyelectrolytes which are produced by polycondensation of alkyl halides with amines. For example, a particularly suitable polyamine is prepared by polycondensation; Epichlorohydrin with Dimethjlamine. preferably in a molar ratio of 0.71: 1 to 033 : 1. obtain. Other suitable polyamines are described in DE-OS 26 07 866.

When using polyamines such polymers with a molecular weight of 1000 to 100,000 and in particular from 10,000 to 50,000 are preferably used

The compounds show even in very low concentrations of only 0.005% or 0.01% in V / water excellent dust binding properties. The application concentrations depend in detail on the area of application, the dust to be bound and the type of polyelectrolyte away. Concentrations from about 0.005 to 0.20%. Preferably from about 0.01 to 0.10 percent by weight, based on water, will generally produce excellent results.

Another advantage of polyacrylamide products is that they can be supplied as organols and compared to powders have the advantage of being able to be conveyed and added by pumps, which is particularly the case with the Dust control underground is of importance, since dust nuisance from powder from the start turn off! can be.

Although the invention may be advantageously applied to various fields, their use leads to very special significance in the wet dust control in coal mines.

The most important and most effective way is wet dust control immediately when the dust is generated. Once the dust has got into the weather stream, precipitation is hardly possible any more. Due to the influences on the mine climate and the coal purification surface (sighting) there are limits to wet dust control, because the water content of the raw coal should not exceed 6%. The aim is therefore to use little water v ^; El to fight dust as soon as it arises. When the coal is soaked, water is pressed through boreholes into the pending coal.The water spreads sicii in the seam on the bad, pressure layers and stratified areas on all sides, binds the dust already present here and reduces the release of suspended dust during the crushing work during extraction .

As a guideline for the amount of drinking water, the Table I.

Coal impregnation method a water quantity of approx. 10 ^{l / fm 3} coal (fm ³ = solid cubic meter). It is important that the water is evenly distributed and that the contact between coal and drinking water is as intensive as possible.

In principle, every seam can be soaked, the only differences being in the water absorption of the Consist of coal. It is determined by the type of coal and the structure of the seam (bad system, Hardness, type of pores, etc. a). The best water intake structure owns the solid coal, to flame coal and anger Anthracite takes it off.

Due to the soaking work, the moisture in the coal is increased only relatively slightly by approx. 1% from about 5% to 6% water.

Dust control by atomizing water takes place at various operating points:

- Roller nozzles on cutter rollers

- Planing alley spraying during planing operation

- Spraying or sprinkling of conveyor belt transfers

- Spraying of drifting machines

In all jet runs, emphasis is placed on that the actual source of dust is sprayed directly. Dust that has already formed and is in the Wetters'rom is located, is not even by spraying to capture more. because the likelihood of one Water trough; xhen a dust particle hits only a very small amount in the free space H?

It has now been found that relatively large water droplets are more effective than smaller droplets. Small Water droplets can be carried away by the vetting speed and are then used for dust control ineffective and have a negative impact on the mine climate. Through the use according to the invention the special polyelectrolyte becomes the water drop configuration favorably influenced

When spraying planes and rollers, amounts of water are used which are in the order of magnitude of 100-2001 / min = 6-12m ³ / h. As a rule, the existing water is brought to 30-40 bar with pressure increase pumps and, depending on the actual running time of the mining machine, is sprayed through nozzles on the roller or the plows onto the coal that is being mined

According to the invention, improvements in the binding of dust have been made to the impregnation of coal more than 50% achieved

In the following table I the results of the dust control by spraying on a roller on a shaft system using the specified additives in a concentration of 0.0Wo are shown . It can be seen that, compared with spraying without additives, a 37% or 63% improvement is achieved with the compounds used.

Additional media

Water tightness

particulate matter

Fumed silica

effect

Without 108 l / min 5.9 mg / m ³ 0.58 mg / m ³

Copolymer sus
75% acrylamide

25% dimethylaminoethyl meth- 1161 / min XL mg / m ³ 0.17 mg / m ³ 63%

acrylate

continuation

"Additional Miuel

Amount of water

Fine dining

Fumed silica

effect

Copolymer from 70% acrylamide 30% acrylic acid

110 l / min

3.7 mg / m ³

0.29 mg / m ³

37%

For the dosage; .desj additives have various DOsierungssysterne proven to be useful: z. B. Electric piston or diaphragm pumps (made of stainless steel) controlled by contact water meters or can be locked with this in connection with booster pumps; Dosing pumps that controlled via the drive shaft of the booster pumps: injectors that are on the suction side of Booster pumps or, if the pressure is sufficiently constant, built into the normal water pipe can be; and batch tank with float circuit and injector metering, which can be used as a template for Booster pumps are suitable for small amounts of water (e.g. drinking troughs).

A preferred embodiment of the method is that a solution of the polyelectrolyte is used, which has been made by inversion of a latex of polyelectrolysis in water ··

The simplest method is dosing with injectors. Since injectors, however, only under certain conditions Working conditions (water flow, water di ick), this method is not universal. For the metering of polymers, the electric metering pump in combination with injectors (shear, inversion) in question, whereby the Polymers as a concentrated latex can be added via the injector into the suction line of the pump.

The addition of the polyelectrolyte in the form of a concentrated latex via a metering pump in Combination with static mixers is therefore particularly advantageous

F i g. 1 schematically illustrates the use of polyelectrolytes in carbon impregnation. While drinking coal the coal to be cut is wetted by pressing water through it Measure should include the dust generated during the mining of the coal can be reduced.

In order to increase the dust-binding capacity of the water, for example, a compound based on polyamm was added to the water. The product is metered using an injector. The concentration was 1 liter of polyelectrolyte per 1 m ^{3 of} water. Without the polyelectrolyte, the fine dust concentration was 20.4 mg / m ³ , while the use of the polyamine enabled an approx. 50% reduction to 103 mg / m ^{3 to} be achieved.

FIG. 2 likewise schematically illustrates the use of polyelectrolytes in the spraying. To combat dust during the mechanical mining of coal, water is atomized on the mining machines (rotary cutter loader or planer) .To increase the dust-binding capacity of the water, a compound based on polyacrylamide was added to the water, for example was coupled with the booster pump for the roller nozzle. The concentration was 0.1 liter of polyelectrolyte per 1 m ^{3 of} water. In order to have a good

to guarantee schung, was that; Product over a Mixing pipe injected into the water pipe The dust reduction achieved results from the following comparison:

Dust reduction: Fine dust concentration without polyelectrolyte = 5.9 mg / m ³ .
Fine dust concentration with polyelectrolyte 2.2 mg / m ³ = 63% reduction

F i g. 3 shows a schematic diagram for the application of the method according to the invention in mining.

It has been shown according to the invention that cationic polyelectrolysis is the negatively charged carbon and Recovery particles, which repel each other due to their negative charge, neutralize so that the particles pass through natural van der Waals attractions can coagulate. Higher molecular weight cationic polyelectrolytes have the advantage of having a discharging effect and thus by additionally binding the negative particles to positive ones Valences of the polymer molecule to form even larger agglomerates and the dedusting in addition to influence positively.

Anionic polyelectrolytes also form agglomerates through cross-linking of particles and molecular chains. By combining discharge and crosslinking with two oppositely charged polyelectrolytes, e.g. B. by cationic impregnation and anionic spraying, can be carried out according to the invention, especially with the finest Particles, an even better agglomeral formation achieve. A particularly useful embodiment of the process of the invention therefore consists in using cationically active and anionically active Use polyelectrolytes in combination. Through additional combination with a corrosion inhibitor many other advantages are achieved, since the standstill corrosion in the rollers and the resulting caused blockages at the nozzles can be prevented.

so the droplet size is for optimal dust precipitation taking into account the different weather speeds and other local Conditions essential. The addition of previously used wetting agents to the spray water is of

little success, as the wetting agents give a finer droplet spectrum and thus a higher degree of weather speed and faster evaporation rate is achieved. In contrast, according to the invention the viscosity of the water, depending on the concentration, is preferred to values that correspond to the character of a lubricating oil to 10 to lOOmpas, but also even to over 1000 mpas, which has a positive effect on the Affects atomization properties of the water, so that the atomized amount of water is better used.

The invention and its advantages in the mining sector are illustrated by a few further examples the results of which are summarized below in Table II.

For this purpose 2 sheets of drawings

9 10

Table II

Dust reduction through the use of polyelectrodes

Process polyelectrolyte fine dust reduction

1. Soaking without polyamine *)

2. Soaking without polyamine *)

3. Nozzles without polyacrylamide **)

4. Nozzles without polyamine *)

♦) Condensation polymer from epichlorohydrin and dimethylamine.
**) Copolymer of acrylamide and dimethylaminoethyl methacrylate.

20.4
10.3 mg / m ³
mg / m ³ 50% 9.7
6.2 mg / m ³
mg / m ³ 36% 5.9
2.2 mg / m ³
mg / m ³ 63% 10.7
8.1 mg / m ³
mg / m ³ 24%

Claims (3)

29 12 32 'Patent claims: 1. Wet dust control method using chemical additives on the Based on organic polymers, which are added to the water to increase the dust-binding capacity be identified by the fact that one the water at least one polyelectrolyte from the class of acrylamide polymers, polyamines and their modifications added Z Process according to Claim 1, characterized in that acrylamide polymers are mixed with a Molecular weight from 100,000 to 10 million and polyamines having a molecular weight from 1,000 to 100,000 used 3. The method according to claim 1 or 2, characterized in that a solution of the polyelectrolyte obtained by inversion of a latex of the polyelectrolyte in water is used