GB2243836A - Prevention of the drift of dust - Google Patents

Abstract

A composition is disclosed containing glucomannan as a principal component and also a method using a hydrated glucomannan, both for preventing drift of dust involved in, or apart from, the breakup of a building.

Description

TITLE OF THE INVENTION Agent, and method, for preventing drift of dust

BACKGROUND OF THE INVENTION This invention relates to an agent containing glucomannan as an active component and used for preventing , or apart from,W drift of dust involved inthe breakup of a building and to a , or apart trom, method for preventing drift of dust involved inVthe breakup of a building with the use of the agent.

At the present time, the necessity for breaking up and clearing wooden houses, brick buildings, stone buildings, steel-reinforced concrete buildings, and steel-frame concrete buildings arises from the need for modernization of existing buildings by reconstruction, change of purposes of use of buildings, change of locations of buildings, and elimination of effects of aging from dld buildings, etc.

Particularly, in the breakup of dilapidated buildings, the pollution of the environment with the drift of dust from sprayed asbestos walls and ceilings has been already raising a serious social issue.

An attempt is now being made to study the feasibility of preventing the pollution of the environment due to the drift of such dust, especially asbestos dust, by the spray of a chemical preparation. A method for the prevention of drift of dust which is effective in precluding the occurrence of asbestos dust during the breakup of a building and also the occurrence of secondary to tertiary dust during the treatment of broken-up buildings and is satisfactory in terms of the safety of the agent for the human body, the stability of the agent to resist deterioration and preserve efficacy, and the economy of the treatment with the agent remains yet to be developed. The unavailability of an effective preventive measure has discouraged contractors from undertaking the work of breaking up any building containing walls and ceilings of sprayed asbestos.

SUMMARY OF THE INVENTION The inventors have continued a diligent study in search of a method capable of overcoming a series of the problems mentioned above, and found that a method for the prevention of drift of dust which satisfies the requirements of safety, stability, and economy all round can be provided by harnessing the characteristic of glucomannan.

This invention has been accomplished on the basis of these findings. To be specific, this invention is directed to an agent having glucomannan as an active component and (,or apart from, used tor the prevention ot drift ot dust involved inethe breakup of a building, and to a method for the prevention of ,or apart from, drift of dust involved invthe breakup of a building with the k f necessary, / use of hydrated glucomannkibrin combination with an alkali solution.

DETAILED DESCRIPTION OF THE INVENTION Glucomannan occurs as viscous liquid mannan particles in corms of konjak, for example. The raw material for konjak jelly (powder) prevalent today is obtained by extracting such mannan particles in the pure form through a special process. The hydrated glucomannan obtained by swelling with water is irreversibly coagulated into an elastic gel with an alkaline compound such as Ca(OH)2, Na2CO3, Na2HPO4, NaHCO3 or NaOH. This hydrate is preferably heated to shorten coagulation time. These compounds will be referred to collectively as "coagulants".

Incidentally, the konjak jelly which is obtained by divesting the elastic gel of the residual alkali by rinsing with water is popularly used for food called "Konnyaku" in the Japanese language. The edible konjak jelly (equivalent to "Konnyaku11) has a water content of about 97%.

An object of this invention is to prevent drift of dust V , or apart from,) involved in'the breakup of a building by the application of hydrated glucomannan to the building, making good use of the characteristic of glucomannan to occlude water in an amount of about 40 times the weight thereof and yet form a viscoelastic coagulated substance. For the purpose of this invention, any glucomannan available in the form of ordinary konjak powder, refined konjak powder, or the like, namely without reference to the presence or absence of impurities, can be effectively utilized.

In the application of the agent of this invention for the prevention of drift of dust to a building during the course of breakup, glucomannan and water are indispensable requisites. Desirably, glucomannan is hydrated in advance with water and put to use in the hydrate form for the application to a building during the course of breakup.

However, in the construction of a new building using asbestos building materials, glucomannan can be utilized advantageously by being uniformly incorporated in advance in such building materials. When this building is to be broken up afterwards, the possible drift of asbestos dust will be effectively precluded by applying water alone or in conjunction with a suitable adjuvant to the building by spraying or injection, because glucomannan is hydrated in situ to form hydrated glucomannan.

When glucomannan is used in the hydrate form, the glucomannan concentration in the hydrate is suitably in a range of 0.1 to 2% by weight, though it is not very critical. Depending on concentrations, there arises the possibility that hydrated glucomannan, on contact with a cement-asbestos material in the building, gelatinizes on the surface of the cement-asbestos material and consequently prevents itself from permeating into the cement-asbestos material. When hydrated glucomannan is expected to permeate to the depth of the cement-asbestos material, therefore, the glucomannan concentration of the hydrate is desired to be in the neighborhood of 0.5% by weight in order to ensure efficient use.

The application of hydrated glucomannan to the building during its breakup is specifically attained by any of the following methods, for example. The manner of gelatinizing hydrated glucomannan will be described later.

(1) A method which comprises first injecting hydrated glucomannan into the interior or exterior components (cement-asbestos walls or ceilings, and the like) of a building to be broken up and, when necessary, further coating the surfaces of the interior or exterior components with hydrated glucomannan by spraying, for example, before the work of breakup is started.

(2) A method which comprises continuously spraying hydrated glucomannan onto the building while continuing the breakup of the building.

(3) A method which comprises first spraying hydrated glucomannan onto the building and then allowing the layer of the hydrated glucomannan consequently deposited on the surface of the building to solidify before the work of breakup is started.

(4) A method which comprises using water in the place of hydrated glucomannan in any of the methods (1) to (3) above where glucomannan was already used in the construction of the building as described previously.

(5) A method which consists in suitably combining at least two of the methods (1) to (4) above.

(6) A method which comprises continuously spraying hydrated glucomannan, when necessary, in conjunction with an alkali solution prepared as described more specifically herein below on the torn components of the building and, at the same time, continuing to pack the coated torn components, and disposing of the packed torn components as industrial waste. This method serves the purpose of precluding the occurrence of secondary or tertiary dust.

In short, the use of hydrated glucomannan (inclusive of what is prepared in situ) contemplated by this invention is accomplished by applying hydrated glucomannan to the building at least once before, during, or after the breakup of the building.

By gelatinizing the applied hydrated glucomannan with an alkali solution, the occurrence of dust can be inhibited or the dust already produced can be prevented from being drifted in the air. The gelatinization is attained by adjusting the pH value of the hydrate to within a range of 7.1 to 14 (alkalinity).

During the work of breaking up a building, the gelatinization of the hydrated glucomannan is specifically carried out by any of the following methods, for example.

(1) A method which comprises gelatinizing the hydrated glucomannan in advance with an alkali solution and then applying the gelatinized hydrate to a building to be broken up.

(2) A method which comprises injecting an alkali solution in advance to a building to be broken up.

(3) A method which comprises spraying hydrated glucomannan and an alkali solution simultaneously onto a building during the breakup.

(4) A method which comprises first applying hydrated glucomannan to the building by injection or spraying and subsequently adding an alkali solution thereto by injection or spraying.

(5) A method which consists in suitably combining at least two of the methods (1) to (4) above.

(6) Where a building to be broken up is composed of alkaline building materials (such as concrete materials, mortar materials, and cement-asbestos materials which invariably use lime), the application of hydrated glucomannan in any of the methods described previously to the building automatically induces the in-situ formation of an alkali solution, possibly rendering it no longer necessary to adjust the pH of the hydrated glucomannan with the use of additional alkali solution.

In any event, it suffices to adjust the pH value of the hydrated glucomannan positively or otherwise to a level fit for causing gelatinization of the hydrated glucomannan before, during, or after the breakup of the building.

Optionally, the hydrated glucomannan may incorporate therein suitable adjuvants. The adjuvants which are usable herein include the conventional chemical preparations for preventing drift ofdust [e.g., SERPIFLEX (Serpi of France), FIRECHECK (LPL Company of England), BWE 3000 and BWE 5000 (Better Working Environment, Inc. of U.S.A.), and EPA 55 (American Coatings Corp, of U.S.A.)), deodorants, and coloring agents, for example. These'adjuvants are not specifically discriminated on account of their kinds but are required to refrain from impairing the effect aimed at by this invention.

Of course, the method of this invention can be worked in combination with the conventional method, e.g. which comprises first impregnating the asbestos building materials throughout the entire thickness with such conventional chemical preparations and then allowing the preparations to be diffused in the building materials to be solidified and bound fast.

Example 1

Incorporate here page 8a Preparation of Hydrated Glucomannan A: An intimate mixture of 0.5 part by weight of glucomannan with 100 parts by weight of water was gently stirred for 30 minutes, left standing and swelling for 90 minutes, and then stirred for five minutes, to produce Hydrated Glucomannan A.

Preparation of Hydrated Glucomannan B: An intimate mixture of 2 parts by weight of glucomannan with 100 parts by weight of water was gently stirred for 30 minutes, left standing and swelling for 90 minutes, and then stirred in conjunction with 20 parts by weight of an aqueous 5% Ca(OH)2 suspension for 5 minutes, to produce Hydrated Glucomannan B (having an approximate pH value of 12). This hydrate was put to use by spraying within 20 minutes of the preparation. The reason for this early use of the hydrate is that the hydrated glucomannan, on a protracted standing, gains in viscosity and eventually solidifies to an~extent of jeopardizing the convenience of handling. In other words, when the hydrated glucomannan is left standing, it undergoes gradual gelatinization with rise of viscosity so much as to interfere with uniform spraying.For effective use of hydrated glucomannan, therefore, it is desirable that hydrated glucomannan is prepared in a necessary amount estimated in advance and is sprayed completely within a This invention has been explained mainly with reference to the breakup of a building (Example 2), but it is obvious from the foregoing that this invention can also be used in removing or recovering cement-asbestos from (i) sprayed cement-asbestos walls, ceilings or the like of a building apart from breakup (Example 1), (ii) cement-asbestos layers built in car walls or the like by spraying cement-asbestos (Example 3), or (iii) the like, preventing effectively drift of asbestos dust. In the case of asbestos when in the form of dement-asbestos, no additional alkali is needed, because cement-asbestos contains in itself the lime moiety, as has been described earlier.

prescribed period.

The separation of the cement-asbestos layers from a building by the use of the two hydrates mentioned above was carried out by the following procedure.

1. Hydrated Glucomannan A was applied to the sprayed cement-asbestos'1materials by spraying before the materials were scraped off the substrates (Spray 1) the consequently formed layer of the hydrate was left standing for about one hour, and then the scraping of the materials was started.

2. - Hydrated Glucomannan A was applied by spraying onto the parts to be scraped (Spray 2), while the scraping was continued until completion.

3. The separated cement-asbestos materials were sprayed with Hydrated Glucomannan B (Spray 3) and, at the same time, packed in polyvinyl resin bags, and disposed of as industrial waste in the manner specified.

Test results: 1. Hydrated Glucomannan A applied by Spray 1 permeated into the asbestos sprayed onto walls and ceilings, began to gelatilize in about 20 minutes of the application, gave rise to an elastic coat on the surfaces of the asbestos layers of the walls and ceilings, and shielded these materials against contact with the ambient air.

2. Hydrated Glucomannan A applied by Spray 2 onto the parts to be scraped mingled intimately with the glucomannan applied by Spray 1 and precluded the possibility of asbestos fibers being drifted under the impact of tearing and scraping, for example.

3. Hydrated Glucomannan B applied by Spray 3 coated the surfaces of asbestos fragments dropped on the floor and precluded the otherwise inevitable drift of asbestos dust.

4. The portion of the spray-applied Hydrated Glucomannan A which remained after permeation into the cement asbestos materials fell onto the floor and wetted the floor surface. The excess portion adhering to the surfaces of the cement-asbestos materials similarly wetted the surfaces.

In the cleanup work, the walls, ceilings, and floors already denuded by the scraping were sprayed with Hydrated Glucomannan B, left standing for 30 minutes, and then removed from their substrates. In this case, Hydrated Glucomannan B absorbed water from the materials and attracted fast minute scattered particles and gave rise to an elastic gel.

The experiment described above established the conditions for allowing efficient and smooth progress of the work of separating the spray-applied asbestos which the contractors have hesitated to undertake on account of the pollution of the environment. Thus, the preclusion of'drift of dust was accomplished by the present invention. It was found that even when the method of this invention was worked in combination with the standard process of EPA (U.S.

Environmental Protection Agency), the expenses and the time required for the breakup could be reduced to an extent never attained by any conventional methods.

Example 2 A 35-year old wooden one-storey residential building (2.2 m in width, 2.3 m in height to ceiling, and 3 m in length) provided with a tiled roof and wooden board-lined earth walls and a separate store room was broken up and removed. The weather conditions were fine sky, mild breeze, and ambient temperature of 220C. The store room was separated from a neighboring office building by a distance of 2.5 m and from the nearest residential building by a distance of 6 m. The work of breakup was started at 7 o'clock a.m. and completed at 3 o'clock p.m. It was interrupted by one hours noon recess for workers' rest.

Specifically, the work of breakup was carried out by the following procedure.

1. In a stainless steel vessel having an inner volume of 200 liters, 1 kg of glucomannan and 100 liters of water at 20 0C added thereto were stirred at a rate of 60 r.p.m. for two hours and the resultant mixture and 5 liters of an aqueous 1% Ca(OH)2 suspension added thereto were stirred for 5 minutes, to produce a hydrate (Hydrate A). Hydrate A was sprayed on the inner walls and ceilings of the building with an electric-powered compression pump and, at the same time, the inner walls were broken up and placed in bags of polyethylene resin, during which the inner walls of earth caused absolutely no drift of dust. Then, the tiles of the roof were sprayed with Hydrate A and, at the same time, removed from the shingles and lowered to the ground. Then the shingles were ripped off to expose the ceilings. Hydrate A used totalled 70 kg.

2. The wall boards covering the outer walls of the building were removed. The seven pillars of the building, with partial cuts inserted with a saw, were pulled down with a rope. The torn parts were sprayed with Hydrate B until they had been coated with a layer of the hydrate about 10 mm in thickness and were moved - to and piled up in a vacant space improvised as a store yard at a distnce of 30 m. Hydrate B thus used totalled 50 kg.

Hydrate B had been prepared by placing 1 kg of glucomannan and 60 liters of water at 200C in a stainless steel vessel having an inner volume of 150 liters, stirring them at a rate of 30 r.p.m. for 30 minutes, and then stirring the resultant mixture in conjunction with 5 liters of an aqueous 1% Ca(OH)2 suspension for 3 minutes.

The work of breakup in this example was completed without producing any noticeable adverse effect upon the environment. The workers engaged themselves very comfortably to perform the work of breakup which was prevented from drift of dust. Since the hydrate covered and enclosed the broken-up parts from the building and then solidified in situ, the gelatinized hydrate on the surfaces of the separated parts and fragments was not excessively viscous and refrained from impairing the convenience of handling of such parts and fragments. Since the hydrates were suitably colored, the workers were enabled to tell the thickness of the layer of the hydrates applied by spraying and consequently give rise to a coat of uniform thickness.

Incorporate here page 13a ! Example 3 About 60 Q of Hydrated Glucomannan A was prepared as in Example 1.

This preparation was applied in removing cementasbestos layers formed by spraying and having a thickness of about 5 - 10 mm around the windows, around the ceiling lighting apparatus and beneath the floor synthetic resin tile, of a car.

The hydrated glucomannan was sprayed for about 15 min onto the cement-asbestos layers at a rate of 4 Q/min with the use of a spray (GRACO's ULTRA-1000). The sprayed amount was 1l/m of the layer.

After about 30 min, scraping was begun, which took about 1.5 hours by completion.

The separated cement-asbestos was packed in polyvinyl resin bags and disposed of as industrial waste in the manner specified.

Example 4 10 kg of konjak powder (20 - 60 mesh) was packed in a dampproof paper bag and sealed hermetically.

The product is a commercial form of the composition of the present invention for removing or recovering sprayed cement-asbestos, preventing drift of asbestos dust from the sprayed cement-asbestos.

Claims (1)

1. WHAT IS CLAIMED IS

   (1) An agent for preventing drift of dust involved in the breakup of a building, which comprises glucomannan as a principal component thereof.

   (2) An agent for preventing drift of dust involved in the breakup of a building, which comprises glucomannan and a salt whose aqueous solution manifests alkalinity, said glucomannan and said salt being in such amounts that said agent, when added with water, gives a hydrated glucomannan exhibiting alkalinity and possessing a glucomannan concentration in a range of 0.1 to 2% by weight.

   (3) The agent of Claim 1 or 2, which further comprises one or more selected from the group consisting of a chemical preparation for the prevention of drift of dust, a deodorant and a coloring agent.

   (4) A method of preventing drift of dust involved in the breakup of a building, which comprises applying a hydrated glucomannan in conjunction with an alkali solution to a building to be broken up before, during; or after the work of breakup.

   (5) The method of Claim 4, wherein said hydrated glucomannan is formed in situ.

   (6) The method of Claim 4, wherein said alkali solution is formed in situ.

   Incorporate here page 14a ! (7) An agent for preventing drift of asbestos dust involved in removing a cement-asbestos layer, which comprises glucomannan as active component thereof.

   (8) A method of preventing drift of asbestos dust involved in removing cement-asbestos layer of a building, a car, or the like, which comprises applying a hydrated glucomannan onto the cement-asbestos layer to be removed before or during the work of removing.

   (g) An agent for preventing drift of dust substantially as hereinbefore described with reference to any one of the foregoing examples.

   (10) A method of preventing drift of dust substantially as hereinbefore described with reference to the any one of the foregoing examples.