Patent Application
20180265426
The present invention relates to methods of modifying the density of and thereby extending bulk explosives and, more particularly, to a process of blending oil shale granules with bulk explosives to beneficially modify the explosion velocity thereof.
Using bulk explosives to break apart rock formations is a common practice. The cost of modifying the density of bulk explosives for extending them, however, is very high. Moreover, improper modification of bulk explosives can result in the release of hazardous nitrogen oxides (NOx) gases when detonated. Current methods of modifying and extending bulk explosives resulting in extended bulk explosives that are too soft and have too much moisture, both of which adversely affect the extended bulk explosive's detonation performance. Furthermore, the softness of the blending material currently used creates hazardous dust and compromises the correct blend in the bulk explosive column. Also, excessive moisture can damage the bulk explosive and create NOx.
As can be seen, there is a need for a process of modifying and extending bulk explosives at a lower cost, lower moisture, yet with a sufficient hardness, such as by properly preparing oil shale granulates for blending with bulk explosives.
In one aspect of the present invention, a extended bulk explosive includes a bulk explosive in the form of ANFO Prill; and a content of oil shale granulate blended with said bulk explosive, wherein said oil shale granulate being irregularly shaped, and wherein said oil shale granulate being between 15 to 35 percent weight of the extended bulk explosive.
In another aspect of the present invention, the extended bulk explosive includes a bulk explosive in the form of ANFO Prill; and a content of oil shale granulate blended with said bulk explosive, wherein said oil shale granulate being irregularly shaped, and said oil shale granulate being between 15 to 35 percent weight of the extended bulk explosive, wherein said oil shale granulate ranges in size of 1/32 to ½ inches, wherein said oil shale granulate includes fines less than ten percent weight of the oil shale granulate, wherein said oil shale granulate has a porosity of approximately 0.5, wherein said ANFO Prill has a porosity of approximately 4.0.
In yet another aspect of the present invention, a method of manufacturing extended bulk explosives includes the steps of providing bulk explosive in the form of ANFO Prill; screening a content of oil shale for uniform size of oil shale granulate ranging in size of approximately 1/32 to ½ inches; and blending said oil shale granulate with said bulk explosive until said oil shale granular is between 15 to 35 percent weight of the extended bulk explosive.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.
The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Broadly, an embodiment of the present invention provides a resulting extended bulk explosive and the process for preparing and blending oil shale particulate with bulk explosives, thereby extending it and reducing the detonation velocity of the resulting bulk explosive. Typically, ammonia nitrate with fuel oil has a detonation velocity of 14,000 ft. per sec., though when oil shale is added at approximately 25% it will reduce the detonation velocity to 11,000 ft. per sec. The process includes the proper preparation of oil shale granulates to gain different cost effects and performance levels with predetermined blending percentages. The oil shale granulates may be crushed, screened, dried and prepared for blending in accordance to the disclosure of the present invention.
The present invention embodies a process of preparing oil shale for blending with bulk explosives for reducing the detonation velocity of the resulting bulk explosive 100. Moreover, because of the extra fuel created by the oil shale granulates 10 in the blended bulk explosive, NOx byproduct is reduced and energy can stay in the rock formation longer. This is because the faster the detonation velocity the quicker the pressure will escape the associated rock formation, whereby slower velocity will keep the pressure in the rock longer and create more breakage. Another advantage of oil shale blended bulk explosive is better performance; specifically, the detonation has better fragmentation and reduced vibration. Namely, rock has a sonic velocity of 5,000 to 9,000 ft. per sec. The closer the detonation velocity of the explosion is to the sonic velocity of the rock the increase in fragmentation in the rock, and less excessive fines 12 in the rock will be created, which is beneficial because higher fines 12 can cause loss production and loss of money. Fines 12 include but are not limited to flakes, tiny fragments, and silt-sized particles of minerals. Also, reduced vibration created by the blast will reduce the potential damage to nearby structures.
A method of making the present invention includes the following. First, oil shale may be extracted from a seam of ore in a mine, and then crushed. Second, the oil shale is screened for uniform size, ranging from approximately 1/32″ to ½″. In certain embodiments, the oil shale is triple screened to create the proper size of oil shale granulates 10—approximately 1/32″ to ½″. In certain embodiments, the screening may be continued until reducing the fines 12 to at least below 10% of the total bulk material. The resulting oil shale granules 10 may be dried. In certain embodiments, the moisture content is kept below 4% which is the manufactured moisture level of ammonia nitrate. The porosity of the oil shale may be maintained at approximately 0.50, while the ammonia nitrate has a higher porosity of approximately 4.0, so that the low porosity of the oil shale will not absorb the fuel oil from the ANFO prill 20. Then the oil shale granulates 10 may be prepared for blending with the bulk explosives. In certain embodiments, preparation includes maintaining the hardness of the oil shale granulates 10 above a grind level of fifty, which is the grind level set by industry standards and assures the oil shale will not break down during handling.
A method of using the present invention may include the following. The resultant oil shale granulates 10 may be blended at different percentages to gain different cost effects and performance levels of the resulting bulk explosives 100. For instance, the percentage of oil shale percentage (OSP) has been tested from 15% up to 35%, wherein the savings increases with the increased blend percentage while the detonation velocity declines with an associated increase in the OSP. For example, at 35% blend the detonation velocity will drop to 9,000 ft. per sec.
Referring now to
It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the present invention.
