RU2680994C1 - Water blocking additive and the explosive substance - Google Patents

Abstract

FIELD: blasting operations.SUBSTANCE: invention relates to the water blocking additive for the explosive substance. Said additive is made in the form of a mixture comprising the stearic acid salt based at least one surfactant, at least one substance when interacting with water forming a jelly or gel selected from gum, as well as at least one combustible substance in the form of the polydisperse composition powder, selected from the stalks flour, wood flour, leaf flour, the plants seeds flour, the cereals flour, in the following ratio of components, wt.%: surfactant 3–25, substance when interacting with water forming a jelly or gel, 25–70, combustible substance in the form of the polydisperse composition combustible powder 25–70, sodium tetraborate up to 2. Additive can be used in explosives substance for blasting works in rocks. Said explosive substance is a mixture of components, wt.%: granulated ammonium nitrate or granular porous ammonium nitrate 85–91 with the liquid petroleum product addition 1–2 and the water-blocking additive 7–9.EFFECT: introduction of the additive provides the ammonium nitrate based simplest granular explosives with high water resistance, which increases their performance in the watered boreholes and wells.6 cl, 3 tbl, 4 ex

Description

The invention relates to the field of blasting, and in particular to industrial granular explosives based on ammonium nitrate and can be used in flooded boreholes and wells. In addition, the invention relates to a water blocking additive for explosives.

Class II industrial explosive substance (BB) - granulite - is a mechanical mixture based on granular ammonium nitrate or granular porous ammonium nitrate, with the addition of liquid petroleum product, and is intended for blasting on the earth's surface in rocks with a coefficient of strength on the M scale. M. Protodyakonov to 20, with manual and mechanized loading of dry and pre-drained waterlogged holes, and wells. Granulite is allowed to be used in boreholes and wells with a diameter of at least 60 mm. Granular explosives based on ammonium nitrate, used in the pneumatic loading of boreholes and wells, are classified as non-waterproof explosives, and therefore their field of application is limited to dry faces, or preliminary water reduction or drainage of the wells should be applied.

The closest in combination of features to the proposed invention is a waterproof explosive ANFO, which contains, in addition to nitrate and fuel, a hydrophilic thickener and a hydrophobic compound [patent US 4933029 A, op. 06/12/1990]. Upon contact with water, a hydrophobic component (metal stearates, calcium stearate) repels water from the surface of nitrate, while a hydrophilic thickener (guar gum) simultaneously forms a water-resistant barrier.

The disadvantage of this composition is the scarcity and high price of the components. In addition, this composition is water resistant for a short period of time. The use of the ANFO explosive in waterlogged holes and wells is also unknown from this source.

The objective of the invention is to provide the simplest granular explosives based on granular ammonium nitrate with waterproof properties by introducing a complex additive.

The technical result is the provision of high water resistance, the ability to charge waterlogged holes and wells and thereby increase the efficiency of explosives.

The specified technical result is achieved by introducing into class II industrial explosives - granulites - a complex water blocking additive designed to prevent the dissolution of ammonium nitrate at the walls and bottom in flooded boreholes and wells in underground and opencast mining.

According to the invention, an explosive for blasting in rocks is made in the form of a mixture based on granular ammonium nitrate or granular porous ammonium nitrate, with the addition of liquid petroleum product, and also including a water blocking additive, characterized in that the water blocking additive includes a mixture of at least one surfactant based on salts of stearic acid, at least one substance forming jelly or gel in contact with water, in brane of the gum, and combustible material in powder form polydisperse composition selected from the stalks flour, wood meal, flour leaves, plant seed flour, cereal flour and sodium tetraborate, with the following component ratio, wt. %:

ammonium nitrate - 89-91 liquid oil - 1-2 water blocking additive - 7-9.

According to the invention, a water blocking additive for an explosive substance is made in the form of a mixture comprising at least one surfactant based on stearic acid salts, at least one substance that, when reacted with water, forms a gelatin or gel selected from gum, and at least one combustible substance in the form of a powder of a polydisperse composition selected from stalk flour, wood flour, leaf flour, plant seed flour, cereal flour and sodium tetroborate, in the following ratio of components, ma from. %:

surface-active substance, based on stearic acid salts - 3-25 jelly or gel selected from gums - 25-70 combustible substance in the form of a powder of a polydisperse composition, selected from flour stalks, wood flour, leaf flour, flour seeds of plants, flour cereals - 25-70 sodium tetraborate - up to 2.

The complex water blocking additive is a mechanical mixture:

1) surfactants based on salts of stearic acid — calcium stearate, zinc stearate, magnesium stearate, both individually and together;

2) substances capable of forming jellies and gels when interacting with water: gums - guar gum (E412), tragacanth gum (E413), gum arabic (E414), xanthan gum (E415), karaya (E416), packaging (E417), high molecular weight, swelling in water compounds - sodium salt of carboxymethyl cellulose (CAS 9004-32-4), polyacrylamide (CAS 9003-05-8), gelatin (9000-70-8), both individually and together;

3) a combustible substance in the form of fine powders of polydisperse composition, which can be used flour stalks, wood flour, leaf flour, plant seed flour, cereal flour, with a moisture content of not more than 10%;

4) a crosslinking agent - sodium tetraborate;

5) technological additives affecting the explosive, rheological, operational properties in an amount of 0-10%.

Mass fraction of components in a water-blocking hydrophobic-hydrophilic additive: stearate (s) in total 3-25; gum (s) a total of 25-70; flour 25-70; sodium tetraborate to 2; microspheres 0-5; AGP aluminum granules 0-8; technological additives 0-10.

A comprehensive water-blocking hydrophobic-hydrophilic additive is made depending on the requirements for water resistance, flowability, energy and other significant qualitative properties.

When charging a well or a hole, water, in contact with the additive, turns it into an insoluble substance that impedes the penetration of water into the charge.

Justification of the choice of components for a water blocking additive.

Stearates

Salts of stearic acid have pronounced hydrophobic properties - they are poorly wetted by water and have a water-repellent effect. To give the water blocking additive hydrophobic water-repellent properties, stearic acid salts are used - magnesium, calcium, zinc stearates. They make it possible to reduce the rate of penetration of water into the thickness of the additive, up to imparting full hydrophobicity while maintaining water blocking properties for an indefinitely long time in the practical sense (several hours, days, weeks). The degree of hydrophobicity may vary depending on the purity of the product, elemental composition, size (fineness) of the grinding.

Stearates in the form of a fine powder are easily fixed on gum particles and flour particles, form a spatially distributed structure of material points from a hydrophobic component, the free penetration (flow) of water between which is difficult as a result of the inverse capillary effect. Thus, the additive is given properties that make it impossible for the capillary flow of water through the free space of the additive (air gaps). Water, being poured onto the additive from above or from the side, does not wet the hydrophilic parts of the additive and for some time is kept at a certain distance equal to or greater than the radius of the capillary network between the particles of the hydrophobic agent. For water to penetrate deep into such an additive, a small pressure is required - tens of cm of water column, determined by the content of the hydrophilic agent in the additive, its purity and origin.

In addition to the qualitative indicators of stearates as a hydrophobic agent, the requirements for the hydrophobicity of the additive itself can affect their quantitative content in the additive. The higher the requirements for hydrophobicity, the correspondingly higher the content of stearates and the higher the required quality.

In general, the hydrophobic properties from the addition of stearates begin to be noticeably expressed at a stearate content of about 3%, followed by a sharp increase in hydrophobic properties to a content of 25%. After that, the addition of stearates is not so effective and has no practical value.

Gums.

Gums are an extensive class of organic compounds of plant origin. Gums are used as thickeners and structure-forming agents. One of the most important properties of gums is the rate of swelling in water. The swelling rate strongly depends on the origin of the gum, its brand, and the degree of grinding. Depending on the type of gum used, the required degree of water-locking properties of the composition, as well as on the content of the additive in the hot water supply, the amount of gum in the composition of the additive varies widely.

Flour.

To reduce the bulk weight of the water blocking additive, a partial replacement of the water blocking agent (gum) with substances of organic origin having low density and suitable for use as fuel in mixed explosives is used. In the production of explosives, it is possible to use flour of plant origin: flour of stems, tree trunks, leaves, seeds of plants, flour of cereal crops, flour of husk of sunflower seeds, flour of cellulose (waste from cotton production, flax, fabrics, etc.), flour of straw and oilcake . It is also possible to use polymer microspheres, glass microspheres of foamed materials such as foam, etc. materials

Partial replacement of gum with vegetable flour gives more effective water blocking properties, because increases the occupancy of intergranular space.

Flour performs several functions in the supplement. Firstly, it acts as a loosening component, giving the additive a low bulk density. The low bulk density makes it possible to completely fill the intergranular space with a low content of additives in the composition of the hot water supply and thus forms a kind of dry matrix that retains particles of granular explosives in its volume. When the additive gets wet, it turns into jelly, which prevents further penetration of water into the material. The mechanism of water penetration is channel, water penetrates into the thickness of the explosive through intergranular voids. The additive, filling the intergranular space, prevents the penetration of water into the thickness of the explosive.

Secondly, flour as a coarser and fibrous material retains particles of stearates on its surface, giving, in general, water-repellent properties of flour. Despite its hydrophilic properties, at the first instant of wetting time, it has strongly pronounced hydrophobic, water-repellent properties. A branched hydrophobic network appears, which prevents the free penetration of water into the thickness of the additive up to complete non-wettability over time.

The amount of flour can be adjusted waterproof and rheological properties of explosives, as well as bulk density of the additive. Depending on the requirements for the rate of penetration of water through the formed water-resistant layer, a variation is possible between the amount of the water-blocking agent proper (gum) and flour, which serves to increase the occupancy of the intergranular space.

Sodium tetraborate.

Sodium tetraborate is the initiator of the "polymerization" of the resulting water jelly gums of various origins. It acts as a crosslinking agent between the gum molecules, making them less soluble in water, up to a complete loss of solubility (tanning). Depending on the gums used and their amount, the amount of sodium tetraborate varies up to 2 wt. %

Additional components that may be contained in a water blocking additive.

Microspheres.

Microspheres are “hot spots” in the process of propagation of a detonation wave along an explosive charge. The additive, which turned into a jelly, incorporates the components of explosives in which it is used. By its chemical composition, such a jelly can act as an independent explosive capable of decaying detonation. To increase its sensitivity to the initiation and action of a shock wave, microspheres are introduced. Thus, layers containing water adjacent to a dry explosive charge are capable of detonation transformation. Aluminum granules.

AGP aluminum granules are used as a high-enthalpy fuel that increases the heat of explosion. It is used to increase the energy saturation of industrial explosives.

Water-blocking additive may contain microspheres in an amount of up to 5 wt. % and / or aluminum granules in an amount of up to 8 wt. %, i.e. contain them both individually and together.

The following raw materials are used for the manufacture of granite litha:

1) granular ammonium porous porous grade MP according to TU 2143-036-00203789-2003. It is allowed to use granular porous ammonium nitrate according to TU 113-03-00203789-16-93 or TU 2143-635-00209023-99, or TU 2143-639-00209023-99, or TU 2143-029-00203795-2005, or TU 2143 -073-05761643-2013;

- granulated ammonium nitrate according to GOST 2-2013 or according to GOST 14702-79 of the ZhVG brand;

2) liquid petroleum product, including:

diesel fuel of grades A, Z, L, C according to GOST R 52368-2005 or diesel fuel according to regulatory and technical documentation that meets the requirements of the technical regulation of the customs union "On requirements for automobile and aviation gasoline, diesel and marine fuel, jet fuel and heavy fuel oil "013/2011

mineral oil: solar according to OST 38157-74; absorption according to GOST 4540-80; industrial (grades i-5A I-8A, I-12A, I-20A) according to GOST 20799-75;

waste oil products in accordance with GOST 21046-81 that have been cleaned of mechanical impurities.

As a liquid petroleum product, the explosive may contain diesel fuel and / or mineral oil, i.e. both individually and jointly.

Table 1 shows two examples of explosives - granulites - with a water blocking composition and various mass fractions of components. Table 2 shows the controlled physicochemical and explosive characteristics of explosives from table 1. Table 3 shows the main uncontrolled physicochemical and explosive characteristics of explosives from table. one.

Determination of the detonation completeness of explosives is carried out according to GOST 14839.19-69 method A in the following sequence. Granulite is placed in a polyethylene sleeve with one hermetically sealed end face with a diameter of 90 mm. (150 mm for granite lithium on granulated saltpeter GOST 2-2013). The filling of the BB sleeve is carried out with constant shaking. The filling of the sleeve is stopped when the charge height of the explosive becomes equal to 5 charge diameters. After that, an intermediate detonator is installed in the sleeve, consisting of loose or sprinkled from explosive cartridges (ammonal-200, or ammonite No. 6 ZhV) weighing 400 g, and placed from the upper end of the test explosive charge. It is allowed to use checkers T 400G or TG-500 as an intermediate detonator.

Initiation of an intermediate detonator is carried out by an electric detonator, a detonating cord, or non-electric waveguide initiation systems.

The charges are set alternately in an upright position on a site with medium-strength soil and produce an explosion.

Three retests are performed. The completeness of detonation is judged by the presence of a depression in the ground and the absence of explosive residues at the test site.

In the case of incomplete detonation or failure of even one charge, repeated tests are carried out with twice the number of charges. Incomplete detonation or failure is not permitted.

One of the main requirements for hot water supply is near-zero oxygen balance. The amount of oxygen contained in ammonium nitrate should be sufficient to oxidize the combustible substances included in the explosive to CO ₂ , H ₂ O, but the amount of oxygen should not be excessive to prevent the formation of nitrogen oxides. By calculation methods, the ratio of ammonium nitrate is not less than 89-91%, 1-2% diesel fuel and 7-9% water blocking composition.

In addition, the condition for filling the intergranular space in the mixed explosive on the basis of granular ammonium nitrate should be fulfilled to ensure the formation of a waterproof barrier.

Determination of water resistance.

The method is based on measuring the depth of water penetration into the mass of granular explosives for a certain period of time.

Tests are carried out under normal room conditions T = 18 ÷ 22 ° C.

A sample of explosive weighing 400 ± 10 g is weighed and placed in a beaker, the surface of the sample is leveled with a glass spatula with a light seal by tapping the beaker. A paper filter is placed on the surface of the explosive hinge. The diameter of the filter should be 3 ÷ 5 mm larger than the inner diameter of the beaker.

200 ml of water is poured onto a paper filter with a thin stream.

The depth of visible water penetration is measured after 1 hour and 24 hours in at least three places on the outside of the glass, with an accuracy of 1 mm.

According to the measurement results, the arithmetic mean value of the depth of water penetration into the explosive mass in mm / day is rounded to the nearest tenth of a millimeter.

Example 1 (comparative). Water blocking additive has the composition:

pure gum - 98 wt. % sodium tetraborate - 2% wt.

The specified additive is kneaded into the mass of explosives, is evenly distributed throughout the volume.

Such a mixture has a bulk density of about 1 kg / dm ³ . The disadvantage of this composition is the large bulk weight and, therefore, a large flow rate to ensure water blocking properties.

If such a mixture consisting of gum 98 wt. % and a crosslinking agent for 2 wt. % add in the amount of 9 wt. % in the composition of the explosive, then we get a structure with an empty inter-granular space. It is difficult to delay the penetration of water into such a mixture with a practically useful result.

The penetration rate of water (diffusion) in such a composition of explosives, containing 7-9 wt. % of the water blocking composition is 50-75 mm / day.

Example 2 (comparative).

Water blocking additive has the composition:

gum - 45 wt. % sodium tetraborate - 2 wt. % wood flour - 53 wt. % with a density of 250 kg / m ³

Replacing 50% of gum with flour of such a density will reduce the density of the additive by 40%. Replacing gum with flour gives a slight decrease in the water-blocking properties of the additive in absolute value, but allows the additive to fill more inter-granular space, which in turn increases the water-blocking properties to a greater extent than they decrease due to dilution of the additive. In general, this technique allows for the same weight of the additive used to reduce the thickness (distance) of the penetration of water into the explosive.

The disadvantage of replacing gum with flour is a higher diffusion rate of water through such a layer deep into the explosive charge. The mixture has pronounced hydrophilic properties, as a result it is easily wetted by water.

The penetration rate of water (diffusion) in the mass of explosives containing 7-9 wt. % of the water blocking composition is 20-40 mm / day.

Examples of the invention.

Example 3. Water-blocking additive has the composition:

calcium stearate - 5 wt. % gum - 40 wt. % wood flour - 53 wt. % sodium tetraborate - 2 wt. %

The penetration rate of water (diffusion) in the mass of explosives containing 7-9 wt. % water blocking composition is 8-12 mm / day.

Example 4. The water blocking additive has the composition:

calcium stearate - 25 wt. % gum - 28 wt. % wood flour - 45 wt. % sodium tetraborate - 2 wt. %

The penetration rate of water (diffusion) in the mass of explosives containing 7-9 wt. % water blocking composition is 8-12 mm / day.

Analysis of the test results shows that the introduction of a water blocking additive according to the invention into the explosive composition (examples 3-4) can reduce the rate of water penetration into the explosive layer, provide high water resistance, the ability to charge waterlogged boreholes and wells, and thereby increase the efficiency of the explosive. The content of the components within the specified limits is optimal.

Claims (8)

1. A water blocking additive for explosives made in the form of a mixture comprising at least one stearic acid salt-based surfactant, at least one substance which, when reacted with water, forms a gelatin or gel selected from gum, as well as at least one combustible substance in the form of a powder of a polydisperse composition selected from stalk flour, wood flour, leaf flour, plant seed flour, cereal flour, and sodium tetraborate in the following ratio of components, wt. %: surface-active substance 3-25 substance forming in contact with water gel or gel 25-70 powder combustible polydisperse composition 25-70 sodium tetraborate up to 2 2. A water blocking additive according to claim 1, additionally containing microspheres in an amount of up to 5 wt. % and / or aluminum granules in an amount of up to 8 wt. % 3. A water blocking additive according to claim 1, characterized in that the stearic acid salt-based surfactant is selected from magnesium stearate, calcium stearate, zinc stearate. 4. A water blocking additive according to claim 1, characterized in that the substance that forms jelly or gel when interacting with water is selected from guar gum, tragacanth gum, xanthan gum. 5. Explosive for blasting in rocks, made in the form of a mixture based on granular ammonium nitrate or granular porous ammonium nitrate with the addition of liquid oil, and also including a water blocking additive according to any one of paragraphs. 1-4 in the following ratio of components, wt. %: ammonium nitrate 89-91 liquid oil 1-2 water blocking additive 7-9 6. Explosive according to claim 5, characterized in that it contains diesel fuel and / or mineral oil as a liquid petroleum product.