# Workbook 3 - Planning Techniques > **Note**: Please DO NOT WRITE in workbooks. Answer on separate piece of paper. --- ## Section 1: Introduction to Planning **Frame 1.** Safe, efficient blasting procedures (CHECK THE CORRECT ANSWER): - A. have no effect on the mined product or the profitability of the operation. - B. can make the difference between a profitable and a non-profitable mining operation, plus assure the well-being of the workers. - C. are a consideration only in view of the available overburden removal equipment. **Frame 2.** A well-prepared and properly fragmented bench will (CHECK ANY CORRECT ANSWERS): - A. decrease wear and tear on equipment. - B. reduce wasted man hours. - C. provide a safe work site. **Frame 3.** The blasting techniques used in surface mining are (CHECK THE CORRECT ANSWER): - A. the same in all situations. - B. developed as the actual loading of holes takes place. - C. as varied as the types of explosives, equipment used, and products being mined. **Frame 4.** Strata vary greatly across the country, and can also vary in different areas of the same mine property. - A. True - B. False **Frame 5.** The material which covers the coal to be mined (CHECK THE CORRECT ANSWER): - A. can vary from very hard, to very soft. - B. is always consistent in a specific blasting area - all hard or all soft. - C. is not important to blasting. ### Answers to Section 1 1. B is correct 2. A, B and C are all correct answers 3. C is correct 4. A is correct 5. A is correct --- ## Section 2: Burden and Spacing **Frame 1.** The distance from the free face to the first row of holes and the distance between the rows of holes is called the **_____________**. **Frame 2.** The distance between holes in a row is the **_____________**. **Frame 3.** To determine burden, you first need to know the (CHECK THE CORRECT ANSWER): - A. depth of the borehole. - B. spacing. - C. diameter of the borehole. **Frame 4.** One formula for finding burden is (CHECK THE CORRECT ANSWER): - A. spacing times 1.5. - B. diameter of hole (thought of as feet) times 2. - C. diameter of hole times 3. **Frame 5.** One formula used to calculate spacing is: Burden times **_____________** equals spacing. ### Practice Problems - Burden and Spacing **Problem #1:** The borehole to be drilled at a particular blasting site is 15" in diameter. Determine the burden. Answer: Burden = **_____________** **Problem #2:** Calculate the spacing for the blasting pattern described in Problem 1. Answer: Spacing = **_____________** **Problem #3:** Using the burden and spacing calculated in Problems 1 & 2, place the figures in the proper spaces in the illustration. **Problem #4:** Determine the burden and spacing for the hole sizes shown here. - A. 4" hole diameter = **_____** ft. burden and **_____** ft. spacing. - B. 5" hole diameter = **_____** ft. burden and **_____** ft. spacing. - C. 9" hole diameter = **_____** ft. burden and **_____** ft. spacing. - D. 12" hole diameter = **_____** ft. burden and **_____** ft. spacing. ### Answers to Section 2 1. burden 2. spacing 3. C is correct 4. B is correct 5. 1.5 **Problem Answers:** - Problem #1: 30 feet - Problem #2: 45 feet - Problem #3: A. 45 feet spacing; B. 30 feet burden - Problem #4: A. 8 ft. burden, 12 ft. spacing; B. 10 ft. burden, 15 ft. spacing; C. 18 ft. burden, 27 ft. spacing; D. 24 ft. burden, 36 ft. spacing --- ## Section 3: Stemming and Primer **Frame 1.** The primary objective of blasting is to fragment the overburden so it can be removed. - A. True - B. False **Frame 2.** After the hole is properly loaded with explosives a certain amount of the hole must be filled with **_____________**. **Frame 3.** If a hole is improperly stemmed, you will probably have a blowout, causing **_____________** and **_____________**. **Frame 4.** The amount of stemming to be used must be (less than / at least equal to - which?) **_____________** the burden. **Frame 5.** Primers are used to provide the **_____________** necessary for detonation of the main charge. **Frame 6.** The thickness of the primer (that is, from the bottom of the hole to the main charge). **Frame 7.** A rule of thumb for determining the thickness of primer is the formula (CHECK THE CORRECT ANSWER): - A. diameter of hole times 2. - B. diameter of hole divided by 2. - C. burden divided by 10. ### Practice Problems - Stemming and Primer **Problem #1:** You know that the hole diameter is 12 inches. Begin with this figure and determine the: - A. Burden = **_____________** - B. Spacing = **_____________** - C. Stemming = **_____________** - D. Primer = **_____________** **Problem #2:** Repeat the process and do the necessary calculations for a 15-inch diameter borehole. - A. Burden = **_____________** - B. Spacing = **_____________** - C. Stemming = **_____________** - D. Primer = **_____________** **Problem #3:** Look at the illustrations below and place a checkmark to indicate which hole has the correct amount of stemming and primer for a 10 inch borehole. ### Answers to Section 3 1. A is correct 2. stemming 3. airblast, flyrock (IN ANY ORDER) 4. at least equal to 5. energy 6. C is correct 7. B is correct **Problem Answers:** - Problem #1: A. 24 ft.; B. 36 ft.; C. 24 ft.; D. 6 inches - Problem #2: A. 30 ft.; B. 45 ft.; C. 30 ft.; D. 7.5 inches - Problem #3: Borehole "B" has the correct amounts of stemming and primer --- ## Section 4: Powder Factor **Frame 1.** The definition of powder factor is the (CHECK THE CORRECT ANSWER): - A. cubic meter in a borehole. - B. number of pounds of explosives necessary to break a certain quantity of material. - C. pounds or kg of explosives used per cubic foot of material to be fragmented. **Frame 2.** A good average for powder factor is: - A. In a dragline pit (HOW MANY?) **_____________** pounds of explosive or blasting agent is/are required for every two cubic yards. - B. In a shovel pit, one pound of explosives is used for every (HOW MANY?) **_____________** cubic yards. **Frame 3.** To determine the cubic yards per borehole, you must know the burden, spacing, and face height in feet. - A. True - B. False **Frame 4.** The formula for finding cubic yards per borehole is (CHECK THE CORRECT ANSWER): - A. Burden x Spacing x Face Height in feet / 27. - B. Burden + Spacing + Face Height x 27. - C. Burden / Spacing x Face Height. **Frame 5.** A dragline operation usually calls for a powder factor of **_____________**; a shovel operation utilizes a powder factor of **_____________**. **Frame 6.** A product with a density of 1.15 will (sink / float - which?) **_____________** and a product with a density of 0.81 will (sink / float - which?) **_____________**. ### Practice Problems - Powder Factor **Problem #1:** Remember the calculation for the volume of material in cubic yards is: ``` Burden x Spacing x Height (in feet) ───────────────────────────────────── 27 ``` So if the burden is 10', the spacing is 15', and the face height is 30', the cubic yardage to be fragmented by this borehole is **_____________**. Then, let's assume a powder factor of 2 yards per lb. How many pounds of explosives will be used per hole? **_____________** **Problem #2:** Find the pounds of explosives per hole with a 20' burden, 30' spacing, a face height of 100', and a powder factor of 2 yds. per lb. **_____________** **Problem #3:** Using a powder factor of 3 yards per pound, find the number of pounds of explosives to be used in a 975 cubic-yard situation. **_____________** **Problem #4:** Use the loading density chart to determine the pounds of explosives per foot of borehole. - A. 1.25 density, 12" diameter hole = **_____________** - B. 1.45 density, 6.5" diameter hole = **_____________** - C. 0.98 density, 10 5/8" diameter hole = **_____________** - D. 0.80 density, 15" diameter hole = **_____________** ### Answers to Section 4 1. B is correct 2. A. 1; B. 3 3. A is correct 4. A is correct 5. 2 yds./lb., 3 yds./lb. 6. sink, float (IN THIS ORDER) **Problem Answers:** - Problem #1: 166 cu. yds.; 83 lbs./hole - Problem #2: 1111 lbs. explosives per hole - Problem #3: 325 lbs. per hole - Problem #4: A. 61.29; B. 20.86; C. 37.67; D. 61.29 --- ## Instructions for Remainder of Workbook The remainder of this workbook is presented in programmed instruction as described in the Instructions to the program. Remember, answer on your own before you look at the answer provided in the text. This will help you learn faster - and remember the material longer. --- ## Why Different Patterns? **Frame 1.** While many types of patterns can be used in blasting operations, square and staggered patterns are very common in surface coal mining. We've also seen how the use of delays can change a square pattern into a staggered one. So while the driller may see a given pattern as square, the blaster - through the appropriate use of delays - may view that same pattern as **_____________**. **Frame 2.** You also know that, for a 10" diameter hole, the burden should be 20 feet. It should be noted that a square pattern drilled with a 14-foot burden and a 28-foot spacing! Thus, the burden is 6 feet less than the planned 20 feet. So it's obvious that, in laying out the blast holes, you must consider the **_____________** pattern you'll use in the holes. **Frame 3.** Suppose we're dealing with the instance described above ... we want a 20-foot burden, as far as the effects of the blast are concerned ... and we want to shoot on the echelon to place the shot ground in the desired location. To accomplish this, the pattern should be drilled on a 28' by 28' layout. And if we do this, the spacing will be 40 feet, instead of 30. Therefore, instead of being 1.5 times the burden, as we've discussed, the spacing will be (HOW MANY?) **_____________** times the burden. **Frame 4.** The type of equipment used for overburden removal is very important when considering the placement of the broken ground. Therefore, the delay pattern, or firing sequence, must be known, because this is what controls the direction of rock movement. For example, a shovel works in the pit, so delaying on the echelon probably (would / would not - which?) **_____________** be used, since it throws the material toward other shot ground. **Frame 5.** But what about the square pattern? We mentioned earlier that the square pattern is usually shot on the echelon. It then becomes a staggered pattern. We've said before that this pattern is generally used to leave the material standing in place, instead of throwing it into the pit. So on the above drawing, place arrows which indicate the direction of throw. **Frame 6.** As the square pattern is shot on the echelon, notice that the burden or the distance to the free face, is less than the drilled pattern burden. This new burden is called the effective burden. The effective burden is determined by the delay system used. In simple terms, the burden is the distance from the hole to shot ground or the created free face. However, with the staggered pattern, as shown below, there is no reduction in the effective burden when shot down row. Or in other words, real and effective burdens (CHECK THE CORRECT ANSWER): - A. remain the same. - B. vary greatly. - C. cannot be compared. **Frame 7.** When the bench is prepared, care must be taken to make sure that it's wide enough for both the drill and the dragline - and remember, the dragline sits on shot ground. A dragline is primarily designed to move overburden, not dig it. So, when a dragline has to dig, efficiency (increases / decreases - which?) **_____________** and wear and tear on the equipment (decreases / increases - which?) **_____________**. **Frame 8.** However, a shovel working in a pit can do some things that can't be done with a dragline. For instance, a shovel can turn and dig into a highwall, even in a slightly hard area, without much noticeable loss of efficiency. It stands to reason, then, that a greater degree of fragmentation or breakage is required to obtain the maximum efficiency from a (shovel / dragline - which?) **_____________**. **Frame 9.** Front-end loaders have even less digging ability and therefore require even (greater / lesser - which?) **_____________** fragmentation when used as stripping equipment. **Frame 10.** In summary, there are several factors which influence the blasting practices to be used at a specific blasting site. The factors include the (CHECK ANY CORRECT ANSWERS): - A. type of overburden removal equipment. - B. breakage desired. - C. direction of throw. --- ## Parting **Frame 11.** Parting is the rock or material which lies between two seams of the coal being mined. When parting is involved in the mining operation, the blasting technique is somewhat different from that which we've discussed. The shooting of the parting will be done after the upper seam of coal has been removed. **Frame 12.** After the entire procedure for the removal of the top seam has been accomplished in this instance, there are only six feet of rock covering the bottom seam. Due to the shallow depth involved the borehole diameter should be (CHECK THE CORRECT ANSWER): - A. reduced in size. - B. increased in size to break the rock. - C. the same diameter as that used to reach the first seam. **Frame 13.** Now, what we just said is fine - the borehole diameter should be reduced, since there's a reduced amount of overburden (only six feet, in our example). But let's face it: a smaller drill may not be immediately available. And even if it is, it takes time to change to the smaller-sized bit. There is an alternative approach, and it's based on this additional rule-of-thumb: > **"The burden should never be greater than the bench height."** In this case, the "bench height" is the same as the depth of the parting, which is only **_____________** feet. **Frame 14.** Our earlier rule-of-thumb stated that the burden equals two times hole diameter considered as feet. Conversely, this would mean that the borehole diameter could only be one-half of the bench height, considered as inches. With only 6 feet of parting, even this size of borehole - in our example, it would be three inches - might be a bit large, and if bulk ANFO were used, could result in a very violent explosion - one that could produce too much **_____________** and **_____________**. **Frame 15.** So, instead of the usual rule-of-thumb (Burden = 2 x hole diameter), let's keep the latter one in mind - the burden should never be greater than the **_____________** and in this case, the bench height is the depth of the **_____________**. --- ## Pattern Adjustment **Frame 16.** Hard and fast rules could be almost impossible to live with in this business. Every successful mining operation must depend upon the combination of experience, knowledge and sound judgment of its employees. We've talked quite a bit about the planning of blasting techniques, but as is the case with many operations, what works on paper may require some adjustment to be applicable in the field. With these points in mind, it is reasonable to say that (CHECK THE CORRECT ANSWER): - A. once a blasting plan has been established, changes cannot be made. - B. after a careful study of the results of an actual shot, it may be necessary to make pattern adjustments. - C. there would never be a need to make changes because of all the time and effort that goes into the blasting plan. **Frame 17.** After making sure all the holes have been shot, it's important to take a good look at three major factors: 1. Was proper breakage achieved? 2. Was the throw adequate and in the proper direction? 3. Were airblast and vibration levels kept to a minimum? If the answer to any of these questions is "no," some pattern adjustment may be necessary. **Frame 18.** You know that poorly broken rock causes excessive wear and tear on equipment. There have been instances in which teeth, tooth bases, and even the entire lip have been ripped off the bucket. Pattern adjustments may be needed where there: - A. is difficult digging or other indications of poor **_____________** - B. which results in inefficiency and an increase in **_____________** wear and tear. **Frame 19.** If a dragline is to sit on the bench, and rehandle is to be kept at the minimum, the bank should be shot in a manner that (CHECK THE CORRECT ANSWER): - A. will move to the pit. - B. keeps the bank standing in place. - C. will move to the right, or opposite the pit. **Frame 20.** If a dragline has to reach down into the pit, pick up the shot material and rebuild the bench, proper blasting (has / has not - which?) **_____________** been achieved. **Frame 21.** Were airblast and vibration levels kept to a minimum? There was a time when little attention was given to the noise and vibration produced by a blasting operation. During that time, blasting was usually done in isolated areas away from the general public. Those days are gone for good. Drilling and blasting have made a complete turnabout. In fact, the allowable amount of noise and vibration produced by a blast is a major concern for every mining operation. **Frame 22.** These three factors must be considered when determining necessary pattern adjustments: - A. Proper **_____________** - B. Direction of **_____________**; and, - C. Levels of **_____________** and **_____________** --- ## Checklist for Blasting Plan Change **Frame 23.** Now, patterns aren't just changed on a whim. A lot of thought goes into this process. Realistically, the cost involved is one important factor. It must be determined whether the overall cost per ton or cubic yard of material moved versus the drilling and blasting cost is cost-effective. The equipment, manhours and effort required to make these changes are minimal in cost or could be very costly depending on the situation. **Frame 24.** The next items on the checklist are the noise and vibration levels. Were a lot of noise and vibration produced, or were these levels kept to a minimum? It should be pointed out that excessive noise and vibration (do / do not - which?) **_____________** indicate good breakage. Noise and vibration are so important to the blasting operation that an entire module in this series has been devoted to this subject. **Frame 25.** We've talked quite a bit about excessive equipment wear, so you understand that the degree of wear on equipment must be considered, as well as the cost of rehandling shot material. When a dragline has to rehandle the bench that was shot off, and restack it, time is lost. This extra step would be a result of (CHECK THE CORRECT ANSWER): - A. poor shooting. - B. excessive noise and vibration. - C. inefficient equipment operation. **Frame 26.** The condition of the bench also has an influence on the blasting operation. A bad bench will dictate changes in the blasting operation to bring the bench conditions back to those desired. This is important, because a bench which is maintained in a desirable condition creates fewer problems for everyone in the area and (increases / does not affect - which?) **_____________** production efficiency. **Frame 27.** As mentioned, the bench must be kept reasonably level and fairly dry. Water affects every phase of the blasting operation. Water in holes causes problems, too, since explosives (are / are not - which?) **_____________** 100% waterproof, although some are more moisture resistant than others. **Frame 28.** Coal waste is another element which must be checked. Poor backfilling practices are a source of major coal loss. If the explosives are loaded in or on top of the coal, a large area of coal will be pulverized and contaminated with rock. When the coal is loaded, a lot of it will be pushed aside as waste, if the coal is (CHECK THE CORRECT ANSWER): - A. not shot. - B. shot along with the overburden. **Frame 29.** Logically, coal waste can be the result of improper blasting techniques, such as (CHECK THE CORRECT ANSWER): - A. holes which are not backfilled. - B. blowouts. - C. too much explosives. **Frame 30.** Every machine has a cycle time which has been suggested by the manufacturer. This simply means that it just takes so much time for a piece of equipment to pick up its load, get it into position and dump it. The profitability of your mine is based on this cycle time. Therefore, if for any reason, the cycle time is slowed down, the profits from your operation will be (CHECK THE CORRECT ANSWER): - A. unaffected. - B. decreased. - C. increased. **Frame 31.** The cycle time could be increased if the ground is improperly fragmented. Proper blasting techniques will (CHECK THE CORRECT ANSWER): - A. help the machine maintain its suggested cycle time. - B. not affect cycle time. - C. get the job done faster, but is of little importance to the overall operation. **Frame 32.** We've established certain criteria which must be considered before any decision is made to change a blasting plan: | Criteria | |----------| | Overall cost per ton of coal, cubic yard of overburden, versus drilling and blasting costs | | Amount of noise and vibration produced by blasting | | Equipment wear and tear | | Rehandling cost | | Desirable condition of bench | | Water conditions | | Coal waste | | Cycle time of machine | These factors must be weighed carefully to help determine whether the end result warrants the steps necessary to change the blasting plan. --- ## Analyzing Poor Results **Frame 33.** When poor results are achieved from a shot, these results should be carefully analyzed to determine the cause. However, one shot probably won't be enough for a thorough evaluation. It takes more than one shot and a rather (smaller / large - which?) **_____________** shot area to determine whether the ground is being shot as desired. **Frame 34.** When shooting results are poor, the area should be checked to make sure that the holes were drilled according to the blasting plan. It is extremely important that holes be measured and laid out as specified on the plan. Poor breakage could be caused by holes which have been drilled off pattern by only a few feet. We'll show you a little later how a slight deviation changes the blasting results. Accuracy in pattern measurements (CHECK THE CORRECT ANSWER): - A. greatly influences the success of a shot. - B. has little bearing on breakage. - C. is not important unless there's a deviation of more than 20 feet. **Frame 35.** Constant checking and evaluation are an essential part of blasting procedures. Side by side evaluations of shot areas are necessary to determine whether the desired breakage is being obtained consistently. Sudden changes in strata may not have been detected when the blast holes were drilled, but can become apparent when the results of the shots are **_____________**. **Frame 36.** For example, some type of extremely hard material could be located in such a manner that it was missed by the blast. Or the strata could change so abruptly that cap rock is either several feet higher or lower than in the adjacent shot area. Once a situation of this type has been carefully analyzed (CHECK THE CORRECT ANSWER): - A. nothing can really be done to correct it for future shots. - B. it can be determined whether the problem calls for a change in hole loading procedures. - C. different explosives will have to be used. **Frame 37.** If certain changes in strata are causing poor fragmentation, after careful consideration of all the factors mentioned previously, it (CHECK THE CORRECT ANSWER): - A. would be impractical to ever change an established blasting pattern. - B. may be necessary to make adjustments in the blasting plan. - C. would probably be too costly to change a plan just to obtain the desired breakage. **Frame 38.** Good blasting practices are a must to assure good conditions to help maintain production efficiency - and even more importantly, to assure safe working conditions. Shot ground should never be left in a way which would cause the material to fall or slide where persons are required to work. Development of hazardous conditions can often be prevented by a (daily / weekly - which?) **_____________** evaluation of the face, bench, and highwall. **Frame 39.** As mentioned, the bench must be evaluated daily also. In a dragline operation, it is essential that shot material be stacked in a manner which: - A. provides a solid place for the **_____________** to sit; - B. maintains production **_____________**; and, - C. provides **_____________** working conditions for all persons involved. **Frame 40.** And, remember, in a dragline operation (more / less - which?) **_____________** fragmentation is required than when a shovel is used. **Frame 41.** Accurate records of all shots and tests must be kept. One person should be assigned the responsibility of handling this task to avoid the confusion which could result when more than one person takes part in record keeping. These records include such pertinent information as burden, spacing, amount of explosives, time of shot, weather, delay number, and so forth. Careful record keeping also aids in shot analysis, since certain trends (would / would not - which?) **_____________** show up over a period of time. **Frame 42.** It's also important that the information received and recorded be accurate and unbiased. Incorrect or biased information could lead to errors in the adjustment of the blasting **_____________**. **Frame 43.** The record keeping aspect of blasting is so important that an entire workbook has been devoted to this subject later in this series. In that workbook, we'll cover such subjects as equipment records, explosives records, blasting records, and Federal, Provincial, and local requirements. --- ## Why Keep on Pattern? **Frame 44.** Once the pattern has been established, it is very important that the holes to be shot are drilled on pattern. We mentioned earlier that poor breakage (can / cannot - which?) **_____________** be caused by holes which are drilled off pattern. **Frame 45.** The primary reason for keeping on pattern is that when the pattern changes: - A. the **_____________** factor changes. - B. which will result in (overbreakage / underbreakage / both under- and over breakage - which?) **_____________** **Frame 46.** If holes are drilled off pattern so that the burden is reduced, the result would probably be a violent shot producing flyrock. **Frame 47.** On the other hand, excessive vibration and airblast are caused by (CHECK THE CORRECT ANSWER): - A. too little burden. - B. the wrong explosive. - C. too much burden. ### Off-Pattern Example Problems **Frame 48.** Let's work through a couple of problems and see exactly what happens when the holes are drilled off pattern. Notice in the illustration how the second row of holes starts out with a burden of 30 feet but gets off pattern by 5 feet down the row. We've talked about how an increase or decrease in burden changes the powder factor. Let's use the drawing to determine what happens to the powder factor in this case. Remember, you find the pounds of explosives per hole by multiplying the burden times the spacing times the face height - then dividing by 27 (1 cu. yd. = 27 cu. ft.). Now find the cubic yards per hole in our example. Cu. yds. = **_____________** **Frame 49.** Okay, you've got that. But what would happen if we increased both the burden and the spacing by 5 feet (to 35 and 50, respectively), keeping the face height the same (50 feet)? Use these figures to find cubic yards per hole. Cu. yds. = **_____________** **Frame 50.** You can see the difference made in the cubic yardage of material by increasing the burden and spacing by 5 feet. Let's go one step further. We're assuming a powder factor of 2 yd./lb. as in a dragline operation, which tells us that for every 2 cubic yards, we need 1 pound of explosives. Okay, find the amount of explosives needed for each of the cubic yardages you just determined. - A. 2500 cu. yds. = **_____________** pounds of explosives. - B. 3240 cu. yds. = **_____________** pounds of explosives. **Frame 51.** Look at the drawing again. The pattern began as planned. With a powder factor of 2 yd./lb., the holes were loaded with 1250 pounds of explosives. Then, down the row, the pattern got off, but the holes were still loaded with 1250 pounds. To do the same job as was accomplished at the beginning of the row - with the 5-foot increase in both spacing and burden, there would have to be (more / less - which?) **_____________** explosives in each hole. **Frame 52.** In fact, the holes with a burden of 35 feet and a spacing of 50 feet would need (675 / 1620 / 800 - which?) **_____________** pounds to do the same work as 1250 pounds would do with 30 feet of burden. **Frame 53.** These holes were all loaded according to the original plan - 1250 pounds per hole. In the list below, check any statements which describe what could happen in the area where the holes were drilled off pattern. - A. Underbreakage. - B. Overbreakage. - C. Increase in vibrations. - D. Blowouts, airblasts and flyrock. **Frame 54.** Okay, now you've seen what happens when you get off pattern and increase the burden. Let's assume in this instance that the holes were correctly measured and there was a decrease in both the spacing and the burden of 5 feet. Again, we loaded the holes with 1250 pounds of explosives. But in the area where the holes were drilled off pattern, 1250 pounds in the holes would probably be too (much / little - which?) **_____________** to accomplish the desired breakage. **Frame 55.** Let's find out what really happened here. First, let's compare the difference in the cubic yards of material involved. We already know that we're talking about 2500 cu. yds. as established by the pattern. But, where the burden is reduced to 25 feet, and the spacing to 40 feet, the actual cubic yardage involved is **_____________**. **Frame 56.** So, from the beginning of the rows, to the area where the holes are off pattern, we're talking about a difference of (648 / 420 / 350 - which?) **_____________** cubic yards. **Frame 57.** These holes were all loaded with 1250 pounds of explosives... when the holes with a spacing of 40 feet and a burden of 25 feet - 1852 cubic yards - should have been loaded with (more / less - which?) **_____________** explosives to obtain the desired breakage. **Frame 58.** In fact, if you divide 1852 cubic yards by the powder factor of 2, you know that these holes should have been shot with **_____________** pounds of explosives to obtain the results as originally established by the blasting pattern. **Frame 59.** Since all the holes were loaded with 1250 pounds, the holes in the area with reduced burden and spacing were overloaded by about 324 pounds each. In this case, these holes were overloaded (CHECK THE CORRECT ANSWER): - A. deliberately to gain more breakage. - B. because the holes were drilled off pattern. - C. because the blasting plan was incorrect. **Frame 60.** We should probably mention that with an increase in vibration and airblasts - blasting becomes more of a nuisance to the general population within hearing distance of the mine. In other words, an increase in blowouts, airblasts, and vibration usually results in an increase in **_____________** from our neighbours. **Frame 61.** We worked through these problems to stress the importance of staying on pattern. It is important that you are aware of the problems that can develop from even a slight deviation away from the blasting plan. In summary: - A. Powder factor changes cause (underbreakage / overbreakage / both underbreakage and overbreakage - which?) **_____________** - B. Blowouts and airblasts could result from (too much / too little / both too much and too little - which?) **_____________** - C. Excessive or increases in noise and vibration often result in increased **_____________** from the public. --- ## How to Lay Out the Pattern **Frame 62.** A buffer is a shot ground which has not yet been removed and which lies between the blast site and the pit. In these cases, the blaster should lay out the buffer line for the first row of holes in the new shot. A buffer line is frequently used even when an actual buffer doesn't exist. This provides an accurate base line for the measuring of the holes for the remainder of the plan. Let's go through the procedures which assure that the holes will be positioned according to the plan. For our first example, let's use a square pattern which has burden and spacing of fifteen feet. It's easy enough to find the first hole by measuring along the buffer line. In fact, the first row is often done by the engineers. **Frame 63.** Easy - right? It does work out simply on paper. But what happens when you're out in the field? You don't have any squares drawn on the ground to show you where to go. How are you going to position the holes without getting off pattern? Stepping off fifteen feet, or just guessing if the tape measure is in line, could result in holes that are off pattern. If each hole is off by a foot or more, by the time a whole area is drilled, some of the holes could be off pattern by many feet. ### The Triangulation Method **Frame 64.** The triangulation method is used to make the calculation and avoid mistakes which can result in costly errors. Each triangle used is a right triangle, which means a 90-degree angle is formed at the juncture of two sides. This is important, as you'll see shortly, since a formula can be used to determine the length of an unknown side when the lengths of two sides are known. By looking at this triangle, you can tell that if you know the distance from "1" to "2" (line "a"), "1" to "3" (line "b"), and from "2" to "3" (line "c"), and so forth, a pattern could be laid out in precise squares. **Frame 65.** Using the formula **a² + b² = c²** - the standard formula for determining the length of an unknown side of a right triangle - gives you the basis for the triangulation method. For simplicity, we are using a 15-foot square pattern. Okay, let's get started. We know that a² + b² = c², or 15² + 15² = c², so c² = **_____________**. **Frame 66.** Our holes, according to the triangulation method, now look like this: ``` a² + b² = c² or, 15² + 15² = 450 ``` We now know that c² equals 450, so all we have to find out is - what number squared (or times itself) equals 450. In other words, if we find the square root of 450, we'll know the distance from hole "2" to hole "3". ### Square Root Reference Table | N | N² | N | N² | |---|-----|---|-----| | 1 | 1 | 16 | 256 | | 2 | 4 | 17 | 289 | | 3 | 9 | 18 | 324 | | 4 | 16 | 19 | 361 | | 5 | 25 | 20 | 400 | | 6 | 36 | 21 | 441 | | 7 | 49 | 22 | 484 | | 8 | 64 | 23 | 529 | | 9 | 81 | 24 | 576 | | 10 | 100 | 25 | 625 | | 11 | 121 | | | | 12 | 144 | | | | 13 | 169 | | | | 14 | 196 | | | | 15 | 225 | | | Notice that 450 falls between two numbers in the N² column, and the square root (N) falls between 21 and 22. So c² = 450, and c = 21.5 (approximately). **Frame 67.** Try some more examples on your own, using the chart provided. Remember, a² + b² = c². Then use the chart to find the square root (N) number squared which equals "c". **Example A:** - a = 10 feet - b = 10 feet - a² + b² = c² - (1) a² = **_____________** - (2) b² = **_____________** - (3) c² = **_____________** - (4) c = **_____________** **Example B:** - a = 30 feet - b = 30 feet - (1) a² = **_____________** - (2) b² = **_____________** - (3) c² = **_____________** - (4) c = **_____________** **Frame 68.** Use examples A and B and lay out the square patterns by indicating the triangulation method: - A. 10' x 10' Square Pattern - B. 30' x 30' Square Pattern ### Staggered Pattern Triangulation **Frame 69.** It should be apparent after working through these sample situations, that by using the triangulation method for measurement, you can keep a square pattern square. This method, with a little variation, can also be used to keep a staggered pattern true. To make these first calculations simple, we'll use a 10' x 15' staggered pattern. We already know that the distance from A to B is 15 feet. So what we need to find here is the distance from "A" to the midpoint between A and B by 2, which is 7.5'. From this point, shown by "X", to C is 10'. So in the newly created triangle, lines "a" and "b" have been labelled; it's up to you to find the length of line "c" using the triangulation method. So a² + b² will give you the distance between B and C. ``` a = 10 a² = 100 b = 7.5 b² = 56.25 a² + b² = c² 100 + 56.25 = 156 ``` Look at the square root chart and find the number closest to 156 in the N² column. In this case, 156 falls about halfway between **_____________** and **_____________**, so the square root of 156 is **_____________**, which is the length of line c in our triangle. **Frame 70.** On the drawing shown here, lay out the staggered 20' x 30' pattern. **Frame 71.** The two methods we've shown here can be used to lay out any pattern. Just keep the chart handy so you can find the square root numbers quickly. We cannot stress enough the importance of staying on pattern. This is one of the secrets to successful blasting. After you've used the measuring techniques discussed here, they'll become an important part of your daily work habits. --- ## Suggestions for Keeping on Pattern **Frame 72.** Keeping on pattern is an integral part of blasting techniques. All the careful planning and calculations won't be worth much if the holes aren't drilled according to the plan. Just as stepping off the holes allows a lot of margin for error, so does drilling without a spotter. It is difficult for the driller to hit the marker from his point-of-view from the drill. So, when positioning the drill, always use a **_____________**. **Frame 73.** There's no room for guessing in the blasting process. So don't guess where those holes should be drilled, the hole stakes are there for a purpose - use them. If for some reason the stakes are missing, it may be necessary to (CHECK THE CORRECT ANSWER): - A. remeasure to make sure the hole is positioned properly. - B. go ahead and drill unmarked holes so the drill can stay ahead of the shooters. **Frame 74.** This is why it's so important not to run over or remove hole stakes. It took a lot of time and effort to lay out the pattern, and without hole markers of some type, there's no way for the spotter and driller to properly **_____________** the drill. **Frame 75.** After the pattern is laid out, you can keep on pattern by: - A. always using a **_____________** - B. relying on the proper techniques, not **_____________**; and, - C. avoiding running over, damaging or removing the **_____________** **Frame 76.** As mentioned at the beginning of this module, your Instructor will discuss the situations at your mine which differ from those used as examples here. The general rules and suggestions are adaptable to your own operation and are meant to be a starting point upon which experience and knowledge can build. Common sense and good judgment are always important in our industry and must be relied upon heavily, as you'll discover when you work through the remaining modules in this series. You have now completed this module of study. We hope you have enjoyed this study of Planning Techniques - and we hope it has given you a basis for the next module - Blasting Techniques. --- ## Test - Workbook 3 ### Planning Techniques **1.** Safe, efficient blasting procedures: - A. Are a consideration only in view of the available overburden removal equipment. - B. Can make the difference between a profitable and non-profitable mining operation, plus assures the well-being of the workers. - C. Have no effect on mined product or the profitability of the operation. **2.** A well-prepared and properly fragmented bench will: - A. Provide a safe work site. - B. Decrease wear and tear on equipment. - C. Both A and B are correct. **3.** Surface mining blasting techniques are: - A. The same in every situation. - B. As varied as the types of equipment and explosives used. - C. Developed during the loading of the holes. **4.** The layers of material above the coal are called: - A. Stemming. - B. Decking. - C. Strata. **5.** The distance from the free face to the first row of holes and the distance between the rows of holes is called: - A. Burden. - B. Spacing. - C. Stemming. **6.** The spacing is the distance between: - A. Each hole. - B. The rows of holes. - C. Holes in a row. **7.** When determining burden, you first need to know: - A. Spacing. - B. Diameter of the borehole. - C. Depth of the borehole. **8.** What is one formula for finding burden? - A. Diameter of the hole (thought of in feet) times three. - B. Diameter of the hole (thought of in feet) times two. - C. Spacing times 1.5. **9.** One formula used to calculate staggered pattern spacing is: - A. Burden times 1.5. - B. Burden times diameter of the hole. - C. Diameter of the hole times 3. **10.** If a borehole is 12 inches in diameter, the burden would be: - A. 12 feet. - B. 24 feet. - C. 36 feet. **11.** If the burden is 10 feet in a staggered pattern, the spacing will be: - A. 10 feet. - B. 10.5 feet. - C. 15 feet. **12.** After the hole has been loaded with the exact amount of explosives, it must be filled with: - A. Sufficient stemming. - B. Slurry. - C. The proper amount of primer. **13.** The amount of stemming needed must be: - A. At least equal to the burden. - B. Equal to half the burden. **14.** To determine minimum stemming, you must multiply: - A. One half the diameter of the hole by two. - B. The diameter (thought of in feet) by two. - C. The diameter of the hole by 1.5. **15.** If the diameter of a borehole is 14 inches, the stemming would be: - A. 21 feet. - B. 28 feet. - C. 42 feet. **16.** Primers are used to provide the necessary: - A. Pressure to detonate the main charge. - B. Explosives power to detonate the blasting caps in the system. - C. Impact for detonation of the main charge. **17.** The formula for determining the amount of primer: - A. Diameter of the hole divided by two. - B. Diameter of the hole times two. **18.** The thickness of the primer is calculated by: - A. Dividing the depth of the hole by two. - B. Dividing the diameter of the hole by two. - C. Multiplying spacing by two. **19.** If the diameter of the borehole is 20 inches, the thickness of the primer in the bottom of the hole would be: - A. 5 inches. - B. 10 inches. - C. 30 inches. **20.** The definition of powder factor is the: - A. Cubic yards in a borehole. - B. Pounds of explosives used per cubic foot of material to be fragmented. - C. One pound of explosive for every two cubic yards. **21.** In a dragline pit, a good average for powder factor is: - A. Two pounds of explosive for every cubic yard. - B. Two pounds of explosive for every two cubic yards. - C. One pound of explosive for every two cubic yards. **22.** In a shovel pit, a good average for powder factor is: - A. One pound of explosive for every three cubic yards. - B. Two pounds of explosives for every three cubic yards. - C. Two pounds of explosive for every two cubic yards. **23.** To determine the cubic yards per borehole, you need to know: - A. Only the burden and spacing. - B. Just the face height in feet. - C. Burden, spacing and face height in feet. **24.** The formula for finding cubic yards per borehole is: - A. Burden / Spacing X Face Height. - B. Burden X Spacing X Face Height in feet / 27. - C. Burden + Spacing + Face Height / 27. **25.** In order for a product to float on water, it must have a density: - A. Less than one. - B. Equal to one. - C. Greater than one. **26.** The pattern established for the boreholes and the timing of the shots determine: - A. How much vibration and airblast there will be. - B. How the burden will break. - C. The desired direction of throw. **27.** In a square pattern the: - A. Burden and Spacing are equal. - B. Spacing is 1.5 times the burden. - C. Burden is 1.5 times the spacing. **28.** Which of these factors influences the blasting plan? - A. Desired direction of throw. - B. Type of equipment used for overburden removal. - C. Both A and B are correct. **29.** Unbroken centres: - A. Will hamper the process of removing overburden. - B. Layers of material from the top of the ground to be mined. - C. Rock or material which lies between two seams of the coal to be mined. **30.** The definition of parting is: - A. Any material around the coal to be mined. - B. Layers of material from the top of the ground to the coal to be mined. - C. Rock or material which lies between two seams of the coal to be mined. **31.** The drilling of the hole to shoot the parting is done: - A. Before the upper seam of coal has been removed. - B. After the upper seam of coal has been removed. - C. At the same time that the borehole is made for the removal of overburden from the upper seam. **32.** Some pattern adjustments may be necessary if: - A. Proper breakage is not achieved. - B. The throw is inadequate or in the wrong direction. - C. Both A and B are correct. **33.** The amount of noise and vibration caused by blasting: - A. Must be controlled. - B. Is not important, unless complaints are received from the public. - C. Is up to the mine operator. **34.** A dragline having to rehandle and restack a bench that has been shot off is a direct result of: - A. Inefficient equipment operation. - B. Excessive noise and vibration. - C. Poor shooting. **35.** Coal waste can result from improper blasting techniques, such as: - A. Blowouts. - B. Too much explosives. - C. Holes which are not backfilled. **36.** If the cycle time of any machine is slowed down, the profits from your operation will be: - A. Increased. - B. Decreased. - C. Unaffected. **37.** Proper blasting techniques will: - A. Not affect cycle time. - B. Get the job done faster, but is of little importance to the overall operation. - C. Help the machine maintain its suggested cycle time. **38.** Accuracy in pattern measurements: - A. Greatly influences the success of a shot. - B. Has little bearing on breakage. - C. Is not important unless there's a deviation of more than 20 feet. **39.** If certain changes in strata are causing poor fragmentation, it: - A. May be necessary to make adjustments in blasting plan. - B. Would be impractical to change an established blasting pattern. - C. Would probably be too costly to change a plan just to obtain the desired breakage. **40.** Excessive vibration and airblasts are caused by: - A. The wrong explosives. - B. Too little burden. - C. Too much burden. **41.** What is the formula used for determining the layout for a square blast pattern? - A. a + b = c - B. a² + b² = c² - C. a² x b² = c² **42.** The best way to keep on pattern is to: - A. Step off the holes. - B. Assume the tape measure is in line. - C. Use the triangulation method to make calculations. **43.** When parting and a shallow borehole are involved with a shot, the diameter of the borehole should be: - A. The same as the first seam. - B. Reduced in size. - C. Increased, to break the rock. **44.** If the parting is eight inches deep, the diameter of the borehole would be: - A. Four inches. - B. Six inches. - C. Eight inches. **45.** In the case of extremely hard parting, it may be necessary to: - A. Increase the distance of the spacing and burden. - B. Decrease the distance of the spacing and burden. - C. Increase the diameter of the borehole. --- ### Answer Key | Question | Answer | |----------|--------| | 1 | B | | 2 | C | | 3 | B | | 4 | C | | 5 | A | | 6 | C | | 7 | B | | 8 | B | | 9 | A | | 10 | B | | 11 | C | | 12 | A | | 13 | A | | 14 | B | | 15 | B | | 16 | C | | 17 | A | | 18 | B | | 19 | B | | 20 | B | | 21 | C | | 22 | A | | 23 | C | | 24 | B | | 25 | A | | 26 | C | | 27 | A | | 28 | C | | 29 | A | | 30 | C | | 31 | B | | 32 | C | | 33 | A | | 34 | C | | 35 | A | | 36 | B | | 37 | C | | 38 | A | | 39 | A | | 40 | C | | 41 | B | | 42 | C | | 43 | B | | 44 | A | | 45 | B |