Document 5kEnBvbJqJVMY7oy51zVQRmkV
Process, Price, Production (Demand), Reserves, and Applications
When judging an abrasive's overall economic value, components such as abrasive cost, equipment cost, labor cost, cleaning rate, disposal and cleanup expense, and product reusability should be considered.
The following formula was used to determine the total cost of blast cleaning per square foot in a blast abrasive journal article [Better Roads November 1986]:
% e% l CLEANING COSTS{$/SQ.FT.) = ----------------------
X
A = Abrasive flow rate, ton/hr. P = Delivered price of abrasive, $/ton. D = Abrasive disposal cost, $/ton. R = Number of times abrasive is used. E = Equipment costs, $/hr. L = Labor costs, including cleanup, $/hr. X = Abrasive cleaning rate, sq. ft./hr
The same formula was used in another blastjournal article for four nonmetallic abrasives without considering recycling capabilities and disposal costs [Seavey 1985]. Performance quality and productivity tests were conducted on the alternative abrasives coal slag, copper slag, and staurolite in comparison to silica sand. Abrasive flow rates, cleaning rates, profiles, and total operating costs were determined for all of these abrasives from tests using 5/16", 3/8", and W long venturi nozzles on new millscale-bearing steel at nozzle pressures of 60, 80, 100, 120, and 140 psi. The alternative abrasives had faster cleaning rates and reduced labor and total operating costs as reported in this article by Seavey [Seavey 1985].
End-users may implement available information from their particular blasting operation into this formula to demonstrate that the total cost of their blasting operation involves more than the selling price of their abrasive. Time spent on examining a job from all perspectives can offer significant cost savings. This cost savings can be achieved by determining the nature of the surface to be cleaned, defining the cleanliness required for the coating to be used, choosing the proper abrasive, optimizing the use of equipment and personnel, and taking into consideration the conditions and restrictions under which the work will be done [Better Roads November 1986, Seavey 1985]. Tables 7-8 and 10-13 show productivity and cost comparisons for substitute abrasives versus silica sand. Tables 9 and 14 show cost comparisons for garnet and steel grit versus coal slag. Most of these cost comparisons were produced by abrasive substitute producers who obtained information from their customers, consultants that were hired to perform tests on their products versus silica sand, or from their own personnel. Therefore, potential users of the substitutes abrasives may wish to contact the abrasive substitute producers about the tests that were performed or the information that was gathered to obtain greater detail for the data and results in these tables.
Abrasive Sand Staurolite Garnet Olivine Specular hematite Coal Slag Copper Slag
Nickel Slag Crushed Glass Steel Grit Aluminum Oxide
Table 1. Physical Properties of Blasting Abrasives
Shape
Hardness (MOHS)
Bulk Density (lbs/ft3)
Rounded Irregular
5.0-7.0
100
Rounded Irregular
6.5-7.0
128-148
Subangular
7.0-8.0
130-147
Angular Semi-rounded
6.5-7.0 6.5-7.0
90-109 183.5
Angular Angular
6.0-7.0 7.0-8.0
75-100 110
Angular Angular Irregular Angular
Irregular
7.0-8.0 5.5-6.5
40-70 Rockwell C
9.0
110 75 260 120-131
No. Uses
1
1* 5** 3-5* 4-10**
1 6-7**
1 1* many**
1 1
50-100* 200-1500**
3-5* 15-20**
*Some of the more conservative number of uses that have been listed for steel grit, aluminum oxide, and garnet are 50-100, 3-5, and 4-10 [Austin 1991 and Williams, 1986].
**Abrasive blasting suppliers estimates for the number of times that steel grit, aluminum oxide, and garnet may be reused are: 1500, 20, and 10 times; depending on the grade of material that is used. However the maximum number of uses listed by suppliers often rely on ideal field conditions in abrasive blasting such as low moisture, etc. that do not always exist.
If supplier did not mention abrasive as capable of being recycled in product brochures, it was assumed to be an expendable abrasive which could not be recycled.
Source of data is from [Austin 1991; Williams 1986; company brochures and material safety data sheets from suppliers listed in the Supplemental Reference Section XV].
Chemical
Silicon Dioxide (SiO2)** Crystalline-silica(SiO2) Aluminum Oxide (A^OO Specular hematite (Fe2O3) or (FeO)
Calcium Oxide (CaO) Magnesium Oxide (MgO) Titanium Oxide TiO2) Potassium Oxide (K2O) Sodium Oxide (Na2O) Manganese Oxide (MnO) Iron (Fe) Carbon (C) Manganese (Mn) Sulfur (S) Sulfur Trioxide (SO3) Zirconium (Zr) Zircon Oxide (ZrO) Phosphorous (P) Chromium(Cr) Nickel (Ni) Radioactivity Picocuries/gram #MSDS's for results
Sand* 90-100% 49-96%
2
Staurolite
29% <5.0% 45% 14% (Fe2O3)
0.07% 0.75% 4.2% 0.1% 0.18% 0.1%
Table 2. Chemical Composition of Blasting Abrasives*** (by Percent Wei g^)
Garnet
Olivine
Specular hematite
Coal Slag
Copper Slag
Nickel Slag
36-38%
39-46%
<1.0%
45-51%
45%
37-51%
<.8%
<0.3%
<1.0%
<1.0%
0.1%
<0.1%
20-26%
0.2-2.3%
0.34%
14-26%
7.2%
1.5-6.6%
30-33% (FeO) Of (Fe2O3 )
6-11% (FeO) or (Fe2O3 )
98.18% (FeA)
18-21% (F^On)
23.3% (F^On)
12-20% (FeA
1.0-2.0%
0.2-1.2%
0.060%
4.3-8.2%
19.6%
0.5-2.5%
1.0-6.0%
39-49%
0.05%
1.0-2.0%
3.7%
4.7-33%
<=2.0%
0.18%
<1.3%
<1.9%
<1.3%
<1.1%
1.0%
<0.06%
3.3% 1
<0.20% <=1%
3
0.026% 0.026%
<0.4% <0.6%
0.1-0.4% 0.1-0.3%
2
0.011% 0.002% 0.009%
1
15-19.8 5
1
<1.2%
0.1-0.45% 2
*The remaining portion of the silica sand abrasive composition consists of water or moisture content and loss on ignition.
**The silicon dioxide chemical includes both non-crystalline and crystalline silica.
***Source of data is from company brochures and material safety data sheets from suppliers listed in the Supplemental Reference Section XV.
Crushed Glass
72.5%
Steel Grit 0.3-1.3%
Aluminum Oxide
0.5-1.7%
0.16% 0.2% (Fe2Os)
9.18% 3.65%
0.12% 13.2%
92-97% 0.1-1.5% (Fe2Os) 0.14-0.18% 0.23-0.30% 1.6-4.0% 0.05-0.08% 0.07-0.12%
0.39%
>95.0% 0.7-1.3% 0.5-1.3% <0.05%
<0.05% <0.2% <0.2%
1 48
Element
Sand # (2)
Aluminum (Al)* Antimony (Sb)** Arsenic (As)*** Barium (Ba)*** Beryllium (Be)*** Calcium (Ca)* Cadmium (Cd)* Cobalt (Co)* Chromium (Cr)*** Copper (Cu)*** Gallium (Ga)** Iron (Fe)* Lead (Pb)*** Lithium (Li)* Magnesium (Mg)* Manganese (Mn)*** Molybdenum (Mo)*** Nickel (Ni)*** #Samples analyzed by NIOSH 1993-94 #Samples analyzed by [Stettler 1982]
110-2200
ND 1-11 ND ND-4900 ND ND-1.8 ND-4.1 ND-4.4
360-5300 ND ND-1.8 ND-3000 2.6-100 ND
ND 2
0
Staurolite # (4)
200-860
ND ND-10 ND 23-490 ND ND ND-10 ND
220-1300 4-13 ND 4-12 10-13 ND
ND 4
0
Table 3. Range of Values for Elements of Blasting Abrasives (by ug/g)
Garnet # (4)
Olivine # (2)
Specular Hematite
# (1)
Coal Slag # (18)
Copper Slag # (7)
Nickel Slag # (3)
1400-10000
210-950
270
2600-77000
130-37000
2600-33000
ND-500
ND
ND ND
ND
ND-90
ND-1450
ND-180
ND-18
ND-4.8
6.6
13-9900
ND-700
ND-300
ND ND
ND
ND-48
ND-180
ND
630-170000
80-970
210
650-41000
650-140000
1500-1700
ND ND
ND ND
ND
ND
ND-4.6
83-110
6.7
ND-31
31-50
24-870
ND-6.4
45-370
ND
ND-200
ND-2400
540-3700
ND
ND-4.5
3.9
ND-92
1340-6400
17-70
ND-27
3400-140000
36000-47000
230000
4200-74000
3900-140000
36000-320000
ND
ND-64
ND
ND-20
ND-8900
ND-70
ND
ND-7.7
ND
ND-100
ND-30
ND
220-820
200000-260000
310
100-5700
1600-24000
22000-56000
100-700
560-710
190
ND-600
ND-2900
440-1100
ND ND
ND ND-11 ND-480 ND
ND
1900-2400
ND
ND-99
ND-2240
830-2400
42
16
2
2
00
0 12
5
1
*Element data is from bulk samples that were analyzed by NIOSH in 1992-93.
**Antimony data is from one nickel slag and five copper slag bulk samples and gallium is from twelve coal slag bulk samples that were analyzed in a study by Stettler et al in 1982. ***Element data is from bulk samples that were analyzed by NIOSH in 1992-93 and coal, copper, and nickel slag bulk samples that were analyzed in a study by Stettler et al in 1982. ND stands for Non-Detectable. #Number of samples analyzed.
Crush Glass # (6) ND-95
ND ND ND 29-350 ND ND-4 ND-2 ND
ND-26 18-220 ND ND-49 ND-1 ND
ND 6
0
Steel Grit # (8)
ND-500
Aluminum Oxide # (6)
690-1800
ND-350 ND ND ND-2200 ND 40-100 80-3600 440-1500
ND ND-33 ND 10-890 ND ND ND-8 ND
840000-100000 ND-120 ND ND-1700 550-9600 50-700
30-3500 ND-9 ND-53 ND-270 1-230 ND
380-2300 8
ND 6
00
Element
Niobium (Nb)** Phosphorous (P)* Platinum (Pt)* Rubidium (Rb)** Scandium (Sc)** Selenium (Se)*** Silver (Ag)* Sodium (Na)* Strontium (Sr)** Tellurium (Te)* Thallium (Tl)* Tin (Sn)** Titanium (Ti)*** Vanadium (V)*** Yttrium (Y)*** Zinc (Zn)*** Zirconium (Zr)*** #Samples analyzed by NIOSH in 1993-94 #Samples analyzed by [Stettler, 1982]
Sand # (2)
ND-100 ND
ND ND 16-99
ND ND
1.6-230 ND-8.9 ND-3.4 0.74-8.1 ND-5.0 2 0
Table 3 Continued. Range of Values for Elements of Blastin g Abrasives (by ug/g)
Staurolite # (4)
Garnet # (4)
Olivine # (2)
Specular Hematite
# (1)
Coal Slag # (18)
Copper Slag # (7)
Nickel Slag # (3)
10-24
ND-24
ND
30-60
ND-240
39-130
ND
ND-650
ND-1600
80-470
ND
ND-160
ND-30
280
ND
ND ND
31-108
ND-10
ND
ND-700
ND-500
ND
ND
ND ND
ND
ND-5
ND-70
ND
ND
ND ND
ND
ND
ND-6
ND
90-260
ND-130
ND-360
58
80-2200
280-1000
90-7600
210-4600
77-208
5
ND
ND ND
ND
ND
ND ND
ND
ND ND
ND
ND
ND ND
ND-1260
15
390-1000
33-570
3-25
66
88-10000
28-2100
47-250
4-15
2.3-33
ND-12
20
ND-400
ND-160
ND-60
ND-6
ND-31
ND
ND
ND-65
ND-27
ND
2
3-13
26-46
19
ND-240
133-52000
28-210
8-14
ND-22
ND
13
ND-270
ND-850
ND-50
4
42
1
6
22
Crush Glass # (6)
ND ND
ND ND-14 71-640
ND ND
ND-5 ND ND 2-60 ND 6
0
00
0
12
5
10
Steel Grit # (8)
Aluminum Oxide # (6)
850-1200 ND
ND-50 ND
ND-570 ND ND
ND ND 20-570
ND ND ND ND
ND-140 ND-200 ND 40-90 ND 8
0
3-950 ND-14 ND-32 ND-8 2-430 6
0
* Element data is from bulk samples that were analyzed by NIOSH in 1992-93. ** Element data is from one nickel, twelve coal, and five copper slag bulk samples that were analyzed in a study by Stettler et al in 1982 (tin data came only from the one nickel and five copper slag bulk samples). *** Element data is from bulk samples analyzed by NIOSH in 1992-93 and one nickel, twelve coal, and five copper slag bulk samples that were analyzed in a study by Stettler et al in 1982. ND stands for Non-Detectable. # Number of samples analyzed.
Table 4. NIOSH RELs, OSHA PELs, & ACGIH TLVs for Blasting Abrasive Ingredients
Ingredient
NIOSH REL
OSHA PEL
ACGIH TLV
Aluminum Oxide (Al2O3)
NONE ESTABLISHED
15 mg/m3 total 5 mg/m3 resp.
10 mg/m3 total A4
Arsenic (As) metal & inorganic cmpds.
CARCINOGEN 0.002 mg/m3 [15 min]
0.010 mg/m3
0.01 mg/m3 A1
Barium (Ba) soluble cmpds. (except Barium sulfate)
0.5
0.5 0.5mg/m3 A4
Beryllium (Be) metal & cmpds.
CARCINOGEN 0.0005 mg/m3[ceiling]
0.002 mg/m3 [TWA] 0.005 mg/m3 [ceiling] 0.025 mg/m3 [30 min max peak]
0.01 mg/m3 A1
Calcium Oxide (CaO)
2 mg/m3
5 mg/m3
2 mg/m3 A4
Carbon Black (C)
CARCINOGEN 3.5 mg/m3
3.5 mg/m3
3.5 mg/m3
Chromium (Cr) as metal
0.5 mg/m3
1 mg/m3
0.5 mg/m3 A4
Chromium, hexavalent Cr(IV) compounds
CARCINOGEN 0.001 mg/m3
NONE ESTABLISHED
0.5 mg/m3
Cobalt (Co) metal, dust & fume
0.05 mg/m3
0.1 mg/m3
0.02 mg/m3 A3
Copper (Cu) dusts & mists Iron Oxide (Fe2O3) dust & fume
Lead (Pb)
1 mg/m3 5 mg/m3
0.100 mg/m3
1 mg/m3 10 mg/m3
.050 mg/m3
1 mg/m3
5 mg/m3 A4
0.05 mg/m3 A3
CARCINOGEN: The RELs for carcinogens listed in Table 4 still reflect the old NIOSH policy for potential occupational carcinogens (described in Section VI), since the NIOSH Pocket Guide to Chemical Hazards still reflects this policy. Changes in the RELs that reflect the new NIOSH policy for potential occupational carcinogens will be included in future editions of the NIOSH Pocket Guide to Chemical Hazards.
A1: ACGIH classified as "Confirmed Human Carcinogen": The agent is carcinogenic to humans based on the weight of evidence from epidemiologic studies of, or convincing clinical evidence in, exposed humans.
A3: ACGIH classified as "Animal Carcinogen": The agent is carcinogenic in experimental animals at a relatively high dose, by route(s) of administration, at site(s), of histologic type(s), or by mechanism(s) that are not considered relevant to worker exposure. Available epidemiologic studies do not confirm an increased risk of cancer in exposed humans. Available evidence suggests that the agent is not likely to cause cancer in humans except under uncommon or unlikely routes or levels of exposure.
A4: ACGIH classified as "Not Classifiable as a Human Carcinogen": There are inadequate data on which to classify the agent in terms of its carcinogenicity in humans and/or animals.
Source: American Conference of Government Industrial Hygienists (ACGIH) [1997] NIOSH [1994a]
Table 4. Continued. NIOSH RELs, OSHA PELs, & ACGIH TLVs for Blasting Abrasive Ingredients
Ingredient
NIOSH REL
OSHA PEL
ACGIH TLV
Magnesium Oxide (MgO)fume
NONE ESTABLISHED
15 mg/m3
10 mg/m3
Manganese (Mn) cmpds. & fume
1 mg/m3 3 mg/m3[15 min]
5 mg/m3 [ceiling]
0.2 mg/m3
Molybdenum (Mo)
NONE ESTABLISHED
15 mg/m3
5 mg/m3 Soluble 10 mg/m3Insoluble
Nickel (Ni) metal & other compounds
CARCINOGEN 0.015 mg/m3
1 mg/m3
1 mg/m3 Insoluble 0.1 mg/m3 Soluble
Phosphorous (P)
0.1 mg/m3
0.1 mg/m3
0.1 mg/m3
Platinum (Pt)
1 mg/m3
NONE ESTABLISHED
1 mg/m3 metal 0.002 mg/m3 soluble salts
Selenium (Se)& cmpds
0.2 mg/m3
0.2 mg/m3
0.2 mg/m3
Crystalline Silica (SiO2): as respirable quartz Crystalline Silica (SiO2): as total quartz Crystalline Silica (SiO2): as cristobalite Crystalline Silica (SiO2): as tridymite Titanium Dioxide (TiO2)
Vanadium (V) as V2O5 dust
Vanadium (V) as V2O5 fume
Yttrium (Yt)& cmpds. Zirconium (Zr) & cmpds.
CARCINOGEN .05 mg/m3
CARCINOGEN .05 mg/m3
CARCINOGEN .05 mg/m3
CARCINOGEN .05 mg/m3
CARCINOGEN
0.05 mg/m3 [15 min.]
0.05 mg/m3 [15 min.]
1 mg/m3 5 mg/m3 10 mg/m3 [15 min.]
10 "`e""
lk x Quartz formula lk x Quartz formula
15 mg/m3 0.5 mg/m3 (resp.) 0.1 mg/m3 (resp.)
1 mg/m3 5 mg/m3
0.1 mg/m3
0.1 mg/m3
0.05 mg/m3
0.05 mg/m3
10 mg/m3 A4
0.05 mg/m3 resp. dust or fume A4
0.05 mg/m3 resp. dust or fume A4
1 mg/m3 10 mg/m3
A4
CARCINOGEN: NIOSH has not identified thresholds for carcinogens that will protect 100% of the population. NIOSH usually recommends that occupational exposures to carcinogens be limited to the lowest feasible concentration.
A4: ACGIH classified as "Not Classifiable as a Human Carcinogen": There are inadequate data on which to classify the agent in terms of its carcinogenicity in humans and/or animals.
Reference:
American Conference of Government Industrial Hygienists (ACGIH) [1997] NIOSH [1994a]
Table 5. 1992 Average U.S. Selling Prices for Other Blasting Abrasives vs Silica Sand
Blasting Abrasive
Price per Ton
Silica Sand
$10-$65
Corn Cob
$225
Nut Shells
$360
Cast Iron Shot
$440
Glass Beads
$500
Sodium Bicarbonate
$900
Sponge
$1,600
Carbon Cut Wire
$2,000
Zirconia Alumina
$2,400
Polymer Carbohydrate
$3,400
Plastic Media
$3,700
Zinc Cut Wire
$4,000
Silicon Carbide
$4,000
Zirconium Silica
$5,000
Aluminum Cut Wire
$6,000
Stainless Steel Cut Wire
$6,500
Source of data is from company brochures from suppliers listed in the Supplemental Reference Section XV, the Paumanock Publications Inc. document entitled "The U.S. Market For Blasting Abrasives - 1992-1997 Analysis [Paumanock Publications, Inc. 1992].
1997 RANGE OF SELLING PRICES
o
H
0LU
01
Q_
FIGURE 1
1997 RANGE OF PRICES/RECYCLE
180
oLU
_l
160
140
> 120
0 LU 100 01 80
o 60 40 H
20
0
Table 6. Location of Major Blasting Abrasive Producers FOB Shipping Points by Abrasive Type
Blasting Abrasive
Major Producers FOB Shipping Points
Sand
MANY
Coal Slag
AL, FL, IL, IN, KS, KY, LA, MD, MN, NH, NJ, OH, SC, TN, TX, VA, WI, WV
Copper Slag
AZ, MT, OR, PA, TX
Steel Grit & Shot
CANADA, MD, MI, OH, PA
Staurolite
FLORIDA
Nickel Slag
OR & MID-CANADA
Crushed Glass
TN, OH, WA
Glass Beads
MO, MI, NJ
Aluminum Oxide
MA, MD, NY
Garnet
BC-CANADA, ID, NC, NY
Specular hematite
Eastern Canada
Corn Cob
IL, OH
Sodium Bicarbonate
CT, NJ, SC, TX
Nut Shells
MO, PA
Plastic Media
CT, IN, NY, TN
Olivine
IN, NC, WA
Cut Wire Shot
CT, MI, NY
Silicon Carbide
MA, NY
Zirconia Alumina
MA
Polymer Carbohydrate
MN
Zirconium Silica
NJ
Sponge
ME
Silica sand and the primary substitute abrasives for silica sand for abrasive blasting are listed in bold print.
Reference: Price lists/brochures from suppliers listed in the Supplemental Reference Section XV and the Bureau of Mines document entitled "Abrasive Materials 1992" [Austin, 1993].
Table 7. E.I. DuPont De Nemours & Company/Chemicals & Pigments Division Cost Comparison: Silica Sand vs. Staurolite
Silica Sand
Staurolite
Abrasive Used (lbs.)
2400
900
Blasting Time (min.)
72 43
Delivered Cost ($/ton)
29 120
Disposal Cost ($/ton)
22 22
Total Prep. Cost ($)
61.20
63.90
Labor Savings
None
29 min. or 40% of time
BACKGROUND:
Table 7 shows the results of an evaluation of DuPont's Starblast versus a silica sand blasting media which was used to clean one side of a 10 feet by 22.5 feet piece of new carbon steel that had weathered. Note that the material cost of preparing one side of steel was essentially equal though the delivered cost of Starblast was over four times that of silica sand. When labor savings is considered, Starblast is more economical. The added benefits from Starblast of low dusting, low silica exposure, better profile, etc. are in addition to the monetary savings obtained from reduced abrasive material and labor costs. The abrasives were not recycled in this test. Further savings may be achieved by recycling abrasives.
Although this information is believed to be accurate, Du Pont recommends that all Starblast applications be analyzed individually. Similar results are possible, but final savings may be more or less than this case. Please consult DuPont or one of its authorized Starblast distributors for more information.
Reference: Staurolite - Supplemental Reference Section XV. E.I. DuPont De Nemours & Company. Chemicals & Pigments. Chestnut Run Plaza. P.O. Box 80709. Wilmington, DE 19880-0709.
Table 8. JPCL Journal Cost Comparison: Silica Sand vs. Staurolite
Silica Sand
Staurolite
Labor Cost to Blast 1000 sq. ft.
$230
$105
Abrasive Cost ($/ton)
$30 $99
Total Cost to Blast 1000 sq. ft.
$310
$190
Abrasive Cost to Blast 1000 sq. ft.
$80
$85
Percent of Total Cost for Labor
74%
55%
BACKGROUND:
Table 8 shows the results of an evaluation of silica sand versus staurolite for a 3/8" nozzle at 120 psi on new millscale bearing steel, using the formula listed below.
%e%l CLEANING COSTS{$/SQ.FT.) = ----------------------
X
A = Abrasive flow rate, ton/hr. P = Delivered price of abrasive, $/ton. D = Abrasive disposal cost, $/ton. R = Number of times abrasive is used. E = Equipment costs, $/hr. L = Labor costs, including cleanup, $/hr. X = Abrasive cleaning rate, sq. ft./hr
This formula was used in a blast journal article for four nonmetallic abrasives without considering recycling capabilities and disposal costs [Seavey 1985]. Performance quality and productivity tests were conducted on the alternative abrasives coal slag, copper slag, and staurolite in comparison to silica sand. Abrasive flow rates, cleaning rates, profiles, and total operating costs were determined for all of these abrasives from tests using 5/16", 3/8", and W long venturi nozzles on new millscale-bearing steel at nozzle pressures of 60, 80, 100, 120, and 140 psi. The nonmetallic alternative abrasives had faster cleaning rates and reduced labor and total operating costs as shown in Figures 8-12 and Tables 6-7 of this journal article [Seavey 1985].
Source is Journal of Protective Coatings & Linings article entitled "Abrasive Blasting Above 100 psi [Seavey 1985].
Table 9. GMA Pty. Ltd./Barton Mines Corporation Garnet Cost Comparison: Garnet vs. Coal Slag @ Shipyard
GMA GARNET
US NAVY COAL SLAG
AREA CLEANED - SQ. FT.
51 50
TIME - MIN.
11.8 18.5
MATERIAL USED - LBS
177 540
ESTIMATED CONSUMPTION - LB/HR
900
1750
CLEANING EFFICIENCY - LB/SQ.FT.
3.47
10.8
CLEANING RATE - SQ.FT./HR
259 162
ABRASIVE COST - $/TON
300 65
DUST GENERATION
VERY LOW
HIGH
TOTAL COST - $/SQ.FT.
$1.17
$1.78
BACKGROUND:
Table 9 shows the results of an evaluation of GMA garnet blasting media which was completed at a large east coast U.S. shipyard during May, 1992. The GMA garnet and a U.S. Navy approved coal slag were compared for production rate, dust generation, anchor pattern, and total blasting cost. The evaluation was carried out on a newly constructed vessel with 8 - 15 mils of primer and protective coat. Yard air was used and was found to fluctuate between 80 - 85 psi at the blast nozzle. Two blasters were employed. Anchor patterns of about 2.0 Mils (1 Mil = 1/1000th inch) were obtained with the GMA garnet, and the "white metal" surface that was cleaned with the garnet was judged to be superior in all ways. Use of higher pressures would result in proportionally higher cleaning rates and slightly deeper anchor patterns. The following formula was used to calculate the cleaning costs for each abrasive in units of $/ft2. The cleaning cost calculations are provided.
APiR+E+L
CLEANING COSTS{$/SQ.FT) =
R--------------
GARNET
.45($300+ $150) + $50 + $50 1 259
COAL SLAG $1.17/#2
.875($65 + $150) + $50 + $50 1 162
$1.78/#2
A = Abrasive flow rate, ton/hr. Garnet = 0.45. Coal slag = 0.875. P = Delivered price of abrasive, $/ton. Garnet = $300/ton. Coal slag = $65/ton. D = Abrasive disposal cost $/ton (assumed $100/ton trucking & disposal + $50/ton cleanup cost = $150/ton total). R = Number of times abrasive is used = 1 (neither abrasive was reused for this task) E = Equipment costs, $/hr (assumed to be $50/ton). L = Labor costs, including cleanup, $/hr (assumed to be $50/ton). X = Abrasive cleaning rate, sq. ft./hr. Garnet = 259. Coal slag = 162. Reference: Garnet - Supplemental Reference Section XV. GMA Pty. Ltd./ Barton Mines Corporation.
Table 10. Unimin Corporation Cleaning Rates: Olivine vs. Competitive Abrasives
Mill Scale Panel Cleaning Rate (Ft2/min)
Painted Panel Cleaning Rate (Ft2/min)
GL20x46 olivine
1.00 1.10
GL30 olivine
1.00 0.85
GL40 olivine
1.00 1.30
GL70 olivine
1.20 0.90
staurolite
1.00 0.88
coal slag
0.95
1.10
silica sand
0.66
0.89
nickel slag
0.95
0.74
garnet
1.00 1.20
BACKGROUND:
Unimin Corporation evaluated the performance properties of its olivine versus competitive abrasives when applied on tight mill scale-bearing steel and on polyamide epoxy-coated steel. Table 10 shows the cleaning rates for both mill scale panels and painted panels using a nozzle pressure of 100 psi pressure using various grades of Unimin Corporation's Green Lightning Olivine versus alternative abrasives. A nozzle pressure of 100 psi was used.
Reference: Olivine - Supplemental Reference Section XV. Unimin Corporation.
Table 11. Les Sables Olimag Inc. Efficiency Analysis: Olivine vs. Silica Sand
ABRASIVE
JJ2 JETMAG 16-60 OLIVINE
WEIGHT
200 LBS
COVERED SURFACE (SQ.FT.)
75.2
TIME
20 MINUTES
CLEANING QUALITY
COMMERCIAL
DUST GENERATION
LOW
ABRASIVE CONSUMPTION (LB/SQ.FT)
2.7
ABRASIVE SPEED (SQ.FT/MIN)
3.8
COST COMPARISON
TIME (BASIS OF 8 HOURS OF WORK WITH SILICA: 1056 SQ.FT/DAY)
4.6 HRS
LABOR, FUEL, AND ABRASIVE EQUIPMENT COSTS ($60/HR)
$276
LBS OF ABRASIVE FOR 1056 SQ.FT
2,851
TOTAL ABRASIVE COST (FOB MONTREAL) SILICA: $70/M.T. OLIVINE: $125/M.T.
$162
TOTAL COSTS
$438
DAILY SAVINGS USING OLIVINE
$193
SILICA SAND 200 LBS 44.3
20 MINUTES COMMERCIAL
HIGH 4.5
2.2
8 HRS
$480
4,752 $151
$631
BACKGROUND:
Table 11 shows an efficiency analysis (Sanivan at Alcan) for daily cost comparisons of Olimag's Jetmag 16-60 synthetic olivine versus silica sand that was printed in an Olimag product brochure. This table shows that other factors besides initial cost can reduce the daily operating costs of a blasting operation. This cost comparison includes reduced labor, fuel and equipment costs along with reduced abrasive material costs.
Reference: Olivine - Supplemental Reference Section XV. Les Sables Olimag Inc.
Table 12. Waupaca Materials/Faulks Brothers Construction, Inc. Cost Comparison: Coal Slag vs. Silica Sand
2040 Blackjack COAL SLAG
2340 SILICA SAND
MATERIAL COST (100# BAG)
$2.76
$1.43
COVERAGE FOR 100#
32 SQ.FT.
10 SQ.FT.
BLASTING COST/SQUARE FOOT
.09
.14
HOURLY BLASTING COVERAGE
240 SQ.FT./HR
75 SQ.FT./HR
BACKGROUND:
In addition to the data shown in Table 12, Waupaca Materials/Faulks Brothers Construction, Inc. includes a letter from the Wisconsin Compensation Rating Bureau (WCRB)in Milwaukee as part of their reference material. WCRB cites "silica sand abrasive blasters would pay $50 per $100 of payroll under workman's compensation code #5469, whereas coal slag abrasive blasters would pay a rate of $10.30 per $100.00 of payroll under workman's compensation code #5474. The savings realized would be about $39.00 per $100.00 of payroll."
Reference: Coal Slag - Supplemental Reference Section XV. Waupaca Materials/Faulks Brothers Construction, Inc.
Table 13. Clemco, Inc. Annual Cost Comparison: Sand vs. Steel Grit
SILICA SAND
STEEL GRIT
Consumption Rate
1,000 lb/hr
2,500 lb/hr
Blasting time 4 hrs/day x 5 days/wk x 52 wks/yr
1,040 hrs/yr
1,040 hrs/yr
Abrasive use (No recovery using 3/8" nozzle
520 tons/yr (.5 tons/hr)
1,300 tons/yr (1.25 tons/hr)
Abrasive use (Using Clemco 3x3 hopper recovery system
520 tons/yr (no recovery)
6.5 tons/yr (200 cycles/ton)
Labor use Loading and unloading
346 hrs/yr (40 min/ton)
13 hrs/yr (15 min/wk)
Abrasive material cost based on average price
$20,800 ($40/ton)
$3,900 ($600/ton)
Labor Cost loading/unloading Average of $15/hr
$5,190
$195
Total annual cost
$25,990
$4,095
Total annual savings using Clemco 3x3 hopper recovery system: $21,985
BACKGROUND:
Table 13 demonstrates why blasting in indoor, enclosed environments should be conducted with a recyclable abrasive such as steel grit. Clemco has a 3x3 hopper recovery system which includes a recessed hopper to collect spent abrasive; a bucket elevator to transport it to an air wash, and a rotary screen abrasive cleaner which returns clean abrasive to the blast machine. It is important to use state-of-the-art blast recovery systems, since leakage of expensive steel grit could cause the abrasive material cost of a blasting operation to increase significantly.
The costs shown in Table 13 decrease as the number of times the abrasive can be recovered increases. Table 13 shows the savings realized by a typical plant after switching from a nonrecoverable abrasive such as silica sand to steel grit, which can be recovered up to 200 times. Using steel grit can be 4 to 5 times less expensive than using silica sand. The figures used in Table 13 are exemplary figures, such as the average price of silica sand of $40/ton. The price of sand varies according to the region of the country where it is sold, but averaged about $24/ton in 1996. However, the selling price range of silica sand is approximately $15-$45/ton. So using $40/ton as the selling price would be using a price from the upper end of the silica sand selling price range.
Note: Exemplary figures only, Clemco Industries Corporation. requests end-users to substitute their own figures to make the above comparison chart applicable to their own blasting operation.
Reference: Steel Grit - Supplemental Reference Section XV. Clemco Industries Corporation.
Table 14. (Materials Performance/Coatings & Linings) Annual Cost Comparison: Nonrecycled Slag vs. Steel Grit
SLAG
STEEL GRIT
Consumption rate
1500 lb/hr
3500 lb/hr
Blasting time (6 hrs/day x 250 days/yr)
1500 MH/yr/operator
1500 MH/yr/operator
Abrasive use/yr (No recovery)
1500 lb/hr x 1500 man-hr/yr ^ (2000 tons/lb) = 1125 tons/yr
3500 lb/hr x 1500 man-hr/yr ^ (2000 tons/lb) = 2625 tons/yr
Abrasive use/yr using SABAR recovery system
1125 tons/yr (No recovery)
17.5 tons/yr (150 cycles/ton)
Abrasive cost/ton (Average price)
$50/ton
$450/ton
Abrasive Materials Cost per operator/yr
1125 tons x $50/ton = $56,250
17.5 tons x $450/ton = $7,875
Total annual abrasive materials cost savings using steel grit: $56,250 - $7,875 = $48,375
Add $50/ton for reduced handling & disposal costs: $48,375 + (1125 tons - 17.5 tons) x $50/ton = $103,750 Total annual savings.
BACKGROUND:
Table 14 shows the cost justification for the use of steel grit and a SABAR system (Steel Abrasive Blasting and Recovery System). The SABAR is a portable blast and recovery system that the manufacturer claimed can be used in normal outdoor blasting situations. This comparison is based on blasting operations that use V2 inch nozzles at 100 psi and 330 CFM. Under these conditions, each operator will use approximately 1500 pounds of sand or mineral slag per hour or 3500 pounds of steel grit per hour. The average delivered cost for one ton of each of the following abrasives is: slag, $50; steel grit, $450. This comparison assumes a total blasting time of 6 man-hours(MH)/day x 250 days/yr = 1500 man-hrs (MH)/yr for each operator. It also assumes that the steel grit will be properly contained and recycled. Labor costs were not included in this cost comparison.
Note: Exemplary figures only, please substitute their own figures to make the above comparison chart applicable to their own blasting operation.
Reference: Geise [1988] Materials Performance/Coatings & Linings Journal.
Table 17. Toxicology Ratings for Blasting Abrasives
Fibrogenic Carcinogenic
Other
Iron oxide -- -
In vitro toxicity (+)
Nickel slag
-
+/-
Contains carcinogenic metals (+)
Copper slag
-
+
Contains carcinogenic metals (+)
Aluminum oxide
+
0
Neurotoxicity (++)
Olivine
+ ++
Immune effects (+)
Coal slag
++ 0
Cytotoxic, inflammatory (+++)
Silica Sand
++++
++
Acute silicosis, cytotoxic, inflammatory (+++)
Crushed glass
0
0
Acute inflammation (+)
Staurolite
00
In vitro & in vivo toxicity (++)
Garnet
00
In vitro & in vivo toxicity (++)
Treated sand
0
0
In vitro & in vivo toxicity (++)
Steel grit
00
0
Scoring: Highly positive Highly negative Equivocal data Insufficient data
++++ -- +/0
Table 18. NIOSH-Recommended Respiratory Protection for Workers Exposed to Respirable Crystalline Silica
Condition
Minimum respiratory protection* required to meet the NIOSH REL for crystalline silica (50 pg/m3)*
#500 pg/m3t (10 x REL)*
Any air-purifying respirator with a high-efficiency particulate filter
#1,250 pg/m3 (25 x REL)
Any powered, air-purifying respirator with a high-efficiency particulate filter, or
Any supplied-air respirator equipped with a hood or helmet and operated in a continuous-flow mode (for example, type CE abrasive blasting respirators operated in the continuous-flow mode)
#2,500 pg/m3 (50 x REL)
Any air-purifying, full-facepiece respirator with a high-efficiency particulate filter, or
Any powered, air-purifying respirator with a tight-fitting facepiece and a high-efficiency particulate filter
#50,000 pg/m3 (1,000 x REL)
Any supplied-air respirator equipped with a half-mask and operated in a pressure-demand or other positive-pressure mode
#100,000 pg/m3 (2,000 x REL)
Any supplied-air respirator equipped with a full facepiece and operated in a pressure-demand or other positive-pressure mode (for example, a type CE abrasive blasting respirator operated in a positive-pressure mode)
Planned or emergency entry into environments containing unknown concentrations or concentrations #500,000pg/m3t (10,000 x REL)
Any self-contained breathing apparatus equipped with a full facepiece and operated in a pressure-demand or other positive-pressure mode, ** or
Any supplied-air respirator equipped with a full facepiece and operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained breathing apparatus operated in a pressure-demand or other positive-pressure mode**
Firefighting
Any self-contained breathing apparatus equipped with a full facepiece and operated in a pressure-demand or other positive-pressure mode**
Escape only
Any air-purifying, full-facepiece respirator with a high-efficiency particulate filter, or Any appropriate escape-type, self-contained breathing apparatus
Only NIOSH/MSHA-approved equipment should be used. t# is less than or equal to; > is greater than. *Assigned protection factor (ApF) times the NIOSH REL. The APF is the level of protection provided by each type of respirator. #These recommendations are intended to protect workers from silicosis; only the most protective respirators are recommended for use with
carcinogens. **Most protective respirators.