MX2008005595A - Explosive formulation. - Google Patents

Abstract

An explosive formulation used in blasting operations such as, but not limited to, mining operations and the like. The formulation is composed of a modified form of Ammonium Nitrate Fuel Oil (ANFO) explosives which have been modified by the incorporation of a solid fuel material. The formulation comprising a dry granular solid component, a liquid high-boiling point component of about 4% by weight, and a solid fuel material. The solid fuel material comprising vitrinite macerals, liptinite macerals, and inert macerals fusinite and semifusinite, and is characterized as (1) having a concentrate of liptinite that is higher than normal coals, and (2) having a concentrate of pseudovitrinite that is significantly lower than normal coals.

Description

EXPLOSIVE FORMULATION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to the field of explosive compositions and methods for making and using same. More particularly, the present invention is an explosive multi-component formulation which finds versatile use in blasting operations such as, but not limited to, mining operations and the like. Even more particularly, though not exclusively, the present invention relates to the manufacture and use of modified forms of Ammonium Nitrate Fuel (ANFO) explosives which have been modified with the incorporation of a solid fuel material. 2. Brief Description of the Prior Art Explosive operations in quarry mining and open pit mining conventionally use ANFO as the explosive. ANFO is an appropriate mixture of ammonium nitrate and fuel oil. While the ANFO remains a popular explosive in the industry, it has inefficiencies and is relatively expensive due to the continually rising costs of its components. In this way, the need remains in the field for other explosive formulations that are safer to use and less expensive than the present explosive compositions. As will be seen from the subsequent description, the preferred embodiments of the present invention overcome the shortcomings of the prior art.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides an explosive formulation of multiple components ie explosives of ANFO which have been modified with the incorporation of a solid fuel material. The present formulation is characterized by a lower detonation velocity, provides results as good as or better than conventional explosives and is less expensive than the explosive compositions currently available. Specifically, the present invention comprises a mixture of ammonium nitrate and less than 4% by weight (decreased by 6% by conventional weight) of fuel oil. The carbon molecules in the fuel oil that are chemically necessary for an optimal explosion are replaced in the current formulation by a solid fuel material characterized as (1) having a liptinite concentration that is higher than normal mineral carbons and (2) having a concentration of pseudovitrinite that is significantly lower than normal mineral carbons. The present invention will be illustrated based on the following description of a preferred embodiment thereof.

BRIEF DESCRIPTION OF THE PREFERRED MODALITY In accordance with the present invention, an explosive formulation is disclosed. The present invention relates generally to a multi-component explosive formulation which finds versatile use in blasting operations such as, but not limited to, mining operations and the like. However, as will be understood, the formulation can be applied to other blasting operations. Specifically, it will be noted that the present invention relates to the application of modified forms of Ammonium Nitrate Fuel (ANFO) explosives which have been modified by the incorporation of a solid fuel material. In the broader context, the explosive composition of the present invention consists of components configured and correlated with respect to others to achieve the desired objective. The present invention provides an explosive formulation consisting of at least three components: a solid, granular, dry component which is an oxidant, a fuel oil or diesel or the like with a high boiling point and a solid fuel material. Each component of the composition of the invention is not individually an explosive. As such, each component can be handled, shipped and stored as either oxidizers or flammable materials. These classifications are shipped more easily and less expensively than explosives. Nevertheless, as will be understood, these components, when mixed, form an explosive formulation which finds versatile use in blasting operations such as, but not limited to, mining operations and the like. The first component of the composition of this invention is a dry component, which is an oxidizing compound. The preferred oxidant is ammonium nitrate which is manufactured and delivered as a spheroid or coated granule having a typical diameter of approximately 0.2286 centimeters (0.09 inches). The first component can be easily selected from oxidants conventionally used in the manufacture of explosive compositions to achieve the desired properties.

The second component of the composition is a liquid component with a high boiling point. In the preferred embodiment, the second component is a liquid fuel. The conventional ANFO generally comprises a mixture of ammonium nitrate and 6% by weight of fuel oil. The present formulation comprises a mixture of the first dry component and less than 4% by weight of the second liquid component. As will be described, the carbon molecules contained in the fuel oil that are chemically necessary for an optimum explosion are replaced in the current formulation by the third component of the composition, a solid fuel material. As used herein, all weights and percentages by weight are based on the total weight of the formulation. The second component can be easily selected from liquid components with a high boiling point conventionally used in the manufacture of explosive compositions to achieve the desired properties. The third component of the composition is a solid fuel material. The main maceral component of the third component (approximately 75%) is vitrinite and also the spinalin liptinite, cutinite and resinite macrals are included. The macérales Fusinite and semifusinite inerts are also present in the third component. As used herein, the term maceral means those organic units that make up the mass of the mineral coal. As such, the mineral coal is composed of macros which each have a different set of physical and chemical properties that control the behavior of the mineral coal. The third component is further characterized as follows: (1) the amount of liptinite macrals, particularly cutinite, is higher than normal and (2) the pseudovitrinite (wood converted to structured charcoal) is almost not present in the third component. More particularly, the normal amount of liptinite macrals in the mineral coal is between 5-15% by weight of the mineral coal. In contrast, the amount of liptinite macrals in the third component is approximately 20%. The vitrinite group generally includes two subgroups specifically matrix vitrinite, also known as desmovitrinite, and pseudovitrinite, also known as telovitrinite. The normal amount of vitrinite macrals in the mineral coal is similar to the amount of vitrinite macrals in the third component, approximately 75% by weight. However, of the 75% in total weight of vitrinite macrals found in the mineral coal, the normal amount of the pseudovitrinite subgroup present is between 25-35%. In contrast, of 75% by total weight of vitrinite macrals in the third component, a very small, almost zero amount of pseudovitrinite is present. Acceptable specimens of the third component are found at the Friendsville Coal Mine at the base of the Mattoon Geological Formation and within the McLeansboro Group of the Missouri Series of the Pennsylvania Geological System of Sedimentary Rocks of Southeastern Illinois. However, alternative solid fuel materials having the characteristics described above can be used. The inherent chemical and physical properties of the third component, as described and used with the first component and the second component, allow the blast velocities to be equal to or closely equal to the natural resonant frequencies of those materials that are burst using which only the energy required to fragment and move the rock and do it in a more efficient, more secure way. These components of the present formulation can be packaged in separate containers that are conventionally employed for the desired purpose. The mixing of the components can be carried out using known mixing means in the field and does not require agitation mechanics. As such, a mixer driven by a motor is not required. Therefore, the mixing of these dry and liquid components to produce the explosive formulation can be done just before the need for the explosive composition. As described, the present invention comprises a mixture of the first component (the dry component) and less than 4% by weight of the second liquid component. The approximate 4% by weight in the present formulation represents a significant decrease in the volume of the liquid component used compared to the conventional use of 6% by weight of the explosives of the prior art. The carbon molecules in the second component that are chemically needed for an optimal explosion are replaced in the current formulation by the third component. The application of a smaller volume of the second liquid component as described reduces the cost of the present explosive formulation compared to the currently available explosive compositions. Similarly, the inclusion of the third component as described decreases the required volume of the first component which further reduces the cost of the present explosive formulation compared to the currently available explosive compositions. The combination ratio of the third component with respect to the ANFO it is a calculation based on the estimated natural resonant frequency of the rock, shale or other material that is bursting. The third component can be combined in ranges of about 5% to 50% of the total weight of the formulation. The formulation is charged and delayed and the firing starts as the conventional ANFO method is known in the field. Now examples of the invention will be provided. There were three components in the blowing agents used in the test, ammonium nitrate mixed with four percent by weight of fuel oil (ANFO-4), the material of the third crude component and the third component material washed with air. As described, the ANFO with only four percent oil was used because the third component material provides additional fuel to the blasting agent mixture. Samples of the third component material were 0.952 centimeters (3/8 inches) less in size. The combinations for each test were made using a powder truck equipped with two product tanks and separate boreholes. The speed of the holes under each deposit could be varied to achieve the appropriate combination. During the test, the ANFO-4 was placed in a tank and the material of the third component was placed in the second tank. The material of each deposit is transported to a series of common collection holes that mix the blasting agents as they are transferred to the blast hole. All drill holes drilled for the test were 25,082 centimeters (9 7/8 inches) in diameter. On average, the holes were 30,195 meters (99 feet) deep with 2,135 meters (7 feet) of backfill, 5,185 meters (17 feet) of backfill and a dust column of 22,875 meters (75 feet). The test holes of the ANFO-4 and the material of the third washed component were placed in the first row along the face of the high wall so that if an explosion failure occurred it would be a minimum amount of material to fire again and move it with a conventional shot. The test holes of the material of the third raw component were incorporated into a production shot and placed in the first row and the second row of the shot. The loads of the face of the high wall varied from 6,710 to 7,320 meters (from 22 to 24 feet) and all the holes were separated by 7.32 meters (24 feet). Each explosion hole was started with a non-electric detonator and a 453.6 gram (16 ounce) detonator. The surface delay between the holes varied from 25 to 50 milliseconds with each explosion having a hole depth delay of 500 milliseconds. The The configuration of all the blast holes in the test is typical of the designs used in normal production shots. The test started with a 4-hole shot of 100% ANFO-4, followed by three 4-hole shots with combinations of 9.1% of the third washed component material and 90.9% of ANFO-4, 21.1% of the third component material washing and 79.9% of ANFO-4 and 29.8% of the material of the third washed component and 70.2% of ANFO-4. The remaining combinations specifically 38.2% of the material of the third component washed and 61.8% of ANFO-4, 51% of the material of the third component washed and 49% of ANFO-4, 14.9% of the material of the third raw component and 85.1% of ANFO- 4, 27.4% of the material of the third raw component and 82.6% of ANFO-4, 41.6% of the material of the third raw component and 68.4% of ANFO-4, 45.3% of the material of the third raw component and 54.7% of ANFO-4 and 55.7% of the material of the third raw component and 44.3% of ANFO-4 were tested with 2-hole perforations. The data collected from each shot was used to produce a speed trace. The detonation velocity can be calculated by choosing two points on the trail or by means of the regression analysis of the complete trail. In this test, the regression analysis preferably that point-to-point data was used because it is believed that more accurately represents the test results. The results of the combinations of ANFO-4 and the material of the third raw and washed component are presented in the following table.

ANFO-4 - 100% ANFO-4 fired well and had an average detonation velocity (VOD) of 3,838.12 meters per second (12,584 feet per second). It was supplied with fuel in a slightly insufficient manner and orange smoke was present at the end of the shot which is typical of that condition. The fragmentation and movement of the fired rock were similar to the production explosions using ANFO with 6% fuel. The ANFO-4 test was conducted to establish a reference index rate for subsequent triggers.

Combinations of the Third Component Material Washed - All washed combinations under test fired well and had constant detonation velocities. There were no explosion failures. There was some smoke White or steam present and surplus fuel continued to burn for a moment after the combination was detonated at 51%. In all the tests, the fragmentation and movement of the rock was similar to the production explosions using ANFO with 6% fuel oil, although it seemed that there was a slight decrease in the fragmentation and movement as the percentage of the material of the third component exceeded 40%. As the percentage of the material of the third component in the combination increased, the detonation velocity decreased. This relationship is almost linear. In general terms, a 1% increase in third component material decreased VOD by 25.01 meters per second (82 feet per second). The highest average speed recorded was 3,843,505 meters per second (12,601 feet per second) for the combination of 9.1% of the third washed component material and 78.9% of ANFO-4. The lowest speed was 2,798.68 meters per second (9,176 feet per second) for the test of 51% of the material of the third washed component and 49% of ANFO-4.

Combinations of the Material of the Third Raw Component - All the combinations of the material of the third crude component under test fired well and had a constant detonation velocity. There were no failures of explosion or there were signs of incomplete combustion. Fragmentation and movement of the fired rock were similar to the results of the third washed component material. As the percentage of the material of the third raw component increased, detonation speed decreased. On average, a 1% increase in third component material decreased VOD by 37.21 meters per second (122 feet per second) which was higher than the third component components washed. The highest average speed recorded was 4,061.99 meters per second (13,318 feet per second) for the combination of 14.9% of the material of the third raw component and 85.1% of A FO-4. The lowest speed was 2,550,105 meters per second (8,361 feet per second) for the 55.7% test of the third raw material and 44.3% of ANFO-4.

Combined Results - The results of the VOD test of the material of the third crude component and washing were comparable. On average, the VOD's of the material of the third crude component were slightly higher than those of the material of the third washed component. This may have been due in part to the smaller size distribution of the material from the third raw component. 23.3% of the material of the third raw component was a mesh 28 less in size comparable with 8.1% for the material of the third washed component. Fragments of smaller size are consumed more easily than the larger particles of the third component material making the detonation process more efficient. The formulation not only reduces the costs of the explosion, but the application of the formulation produced comparable, not to say a better fragmentation, with a higher effective emptying of the material blown up. This results in safer mining conditions due to occurrences of reduced projections. Although the above description contains many specificities, they should not be considered as limiting the scope of the invention but only as providing illustrations of some of the presently preferred embodiments of the invention. For example, the present formulation was described with particular reference to the use of ANFO explosives modified in the rock explosion, however it should be noted that the present invention is not limited to the production and use of this type of explosive, but preferably the The scope of the present invention is more extensive to also include materials, modifications and uses different from those specifically described. Additionally, it will be obvious that the modalities described can be varied in many ways. These variations should not be considered as a divergence of the spirit and scope of the invention and all these modifications as would be obvious to a person skilled in the art are proposed to be included within the scope of the present invention. In this way, the scope of the invention should be determined by the appended claims and their legal equivalents, preferably by the examples given.

Claims (13)

1. CLAIMS 1. An explosive formulation comprising: a solid, granular, dry component, a liquid component with a high boiling point and a solid fuel material, wherein the solid fuel material is characterized in that it contains a vitrinite maceral, maceral of liptinite and the inert fusinite and semifusinite macrosols and where the amount of liptinite macrals is higher than normal and where pseudivitrinite is almost not present in the solid fuel material.
2. 2. The formulation according to claim 1, characterized in that the solid, granular, dry component is an oxidant.
3. 3. The formulation according to claim 2, characterized in that the oxidant is ammonium nitrate.
4. 4. The formulation according to claim 1, characterized in that the liquid component is a liquid fuel oil.
5. 5. The formulation according to claim 4, characterized in that the amount of the liquid component is 4 percent by weight.
6. 6. The formulation according to claim 1, characterized in that the amount of the Vitrinite maceral in the solid fuel material is approximately 75 weight percent.
7. The formulation according to claim 1, characterized in that the solid fuel material is present in an amount of about 5 to about 50 weight percent.
8. 8. An explosive formulation comprising: a solid, granular, dry oxidant component, a liquid component with a high boiling point and a solid fuel material, wherein the explosive formulation is characterized in that the liquid component is not more than 4. % by weight and where the fuel material is mineral coal containing vitrinite and liptinite macrals.
9. 9. The formulation according to claim 8, characterized in that the oxidant is ammonium nitrate.
10. 10. The formulation according to claim 9, characterized in that the liquid component is a liquid fuel oil.
11. The formulation according to claim 10, characterized in that the amount of vitrinite macrals in the solid fuel material is about 75 weight percent of the solid fuel material.
12. 12. The formulation in accordance with the claim 11, characterized in that the solid fuel material is present in the amount of about 5 to about 50 weight percent.
13. 13. An explosive mixture comprising a solid, granular, dry oxidant component, a liquid fuel oil component and a solid fuel material, wherein the explosive mixture is characterized in that the liquid fuel oil is not more than 4% by weight of the mixture and wherein the solid fuel material is mineral coal containing vitrinite and liptinite materials.