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1. Reference Information

A. Purities of Rare Earth Metals and Oxides: Purity on Rare Earth Oxide Basis.

In rare earth industry, chemical purities of rare earth oxides and compounds are often presented on rare earth oxide basis (REO basis), i.e., content of a specific rare earth oxide in comparison to total rare earth oxides (TREO) present: REO/TREO. The statement of "CeO2 > 99%", often means CeO2/TREO > 99%. To obtain its absolute purity of a specific oxide, you can use formula: REO/TREO X Percentage of TREO in the material.

Purity on Rare Earth Metal Basis.

In rare earth industry, chemical purities of rare earth metals are often presented on rare earth metal basis (REM basis)), i.e., content of a specific rare earth metal in comparison to total rare earth metals (TREM) present: REM/TREM. The statement of "Ce > 99%" often means Ce/TREM > 99%. To obtain its absolute purity of a specific metal, you can use formula: REM/TREM X Percentage of TREM in the material.

 B. Price Calculation of Rare Earth Compounds. In rare earth industry, a formula is used to calculate the actual prices of rare earth compounds, such as carbonate, hydroxide and chloride: Actual price of rare earth compound = Price of 100% of TREO (Total rare earth oxide) X Percentage of TREO in the compound. For instance, if price of a cerium carbonate [Ce(CO3)3·xH2O] is quoted as TREO: 45%, Price: $7.63/kg X TREO. Thus, the actual price of the Cerium carbonate is $7.60/kg x 45% = $3.42/kg. C. Powder Sizes

U.S.A. SIEVE SERIES and TYLER EQUIVALENT
Sieve Designation Sieve Opening Nominal
Wire Diameter		 Tyler Screen
Scale Equiv.
Designation
Standard(a) Alternate mm equiv-
alent		 mm equi-
valent
125 mm 5.in. 125 5 8 0.315  
106 mm 4.24 in. 106 4.24 6.4 0.252  
100 mm 4.0 in. (b) 100 4 6.3 0.248  
90 mm 3 1/2 in. 90 3.5 6.08 0.2394  
75 mm 3.0 in. 75 3 5.8 0.2283  
63 mm 2 1/2 in. 63 2.5 5.5 0.2165  
53 mm 2.12 in. 53 2.12 5.15 0.2028  
50 mm 2.0 in. (b) 50 2 5.05 0.1988  
45 mm 1 3/4 in. 45 1.75 4.85 0.1909  
37.5 mm 1 1/2 in. 37.5 1.5 4.59 0.1807  
31.5 mm 1 1/4 in. 31.5 1.25 4.23 0.1665  
26.5 mm 1.06 in. 26.5 1.06 3.9 0.1535 1.050 in.
25.0 mm 1.0 in. (b) 25 1 3.8 0.1496  
22.4 mm 7/8 in. 22.4 0.875 3.5 0.1378 .883 in.
19.0 mm 3/4 in. 19 0.75 3.3 0.1299 .742 in.
16.0 mm 5/8 in. 16 0.625 3 0.1181 .624 in.
13.2 mm .530 in. 13.2 0.53 2.75 0.1083 .525 in.
12.5 mm 1/2 in. (b) 12.5 0.5 2.67 0.1051  
11.2 mm 7/16 in. 11.2 0.438 2.45 0.0965 .441 in.
9.5 mm 3/8 in. 9.5 0.375 2.27 0.0894 .371 in.
8.0 mm 5/16 in. 8 0.312 2.07 0.0815 2 1/2 mesh
6.7 mm .265 in. 6.7 0.265 1.87 0.0736 3.0 mesh
6.3 mm 1/4 in. (b) 6.3 0.25 1.82 0.0717  
5.6 mm No. 3 1/2 © 5.6 0.223 1.68 0.0661 3 1/2 mesh
4.75 mm No. 4 4.75 0.187 1.54 0.0606 4 mesh
4.00 mm No. 5 4 0.157 1.37 0.0539 5 mesh
3.35 mm No. 6 3.35 0.132 1.23 0.0484 6 mesh
2.80 mm No. 7 2.8 0.111 1.1 0.043 7 mesh
2.36 mm No. 8 2.36 0.0937 1 0.0394 8 mesh
2.00 mm No. 10 2 0.0787 0.9 0.0354 9 mesh
1.70 mm No. 12 1.7 0.0661 0.81 0.0319 10 mesh
1.40 mm No. 14 1.4 0.0555 0.725 0.0285 12 mesh
1.18 mm No. 16 1.18 0.0469 0.65 0.0256 14 mesh
1.00 mm No. 18 1 0.0394 0.58 0.02285 16 mesh
850 um No. 20 0.85 0.0331 0.51 0.0201 20 mesh
710 um No. 25 0.71 0.0278 0.45 0.0177 24 mesh
600 um No. 30 0.6 0.0234 0.39 0.0154 28 mesh
500 um No. 35 0.5 0.0197 0.34 0.0134 32 mesh
425 um No. 40 0.425 0.0165 0.29 0.0114 35 mesh
355 um No. 45 0.355 0.0139 0.247 0.0097 42 mesh
300 um No. 50 0.3 0.0117 0.215 0.0085 48 mesh
250 um No. 60 0.25 0.0098 0.18 0.0071 60 mesh
212 um No. 70 0.212 0.00083 0.152 0.006 65 mesh
180 um No. 80 0.18 0.007 0.131 0.0052 80 mesh
150 um No. 100 0.15 0.0059 0.11 0.0043 100 mesh
125 um No. 120 0.125 0.0049 0.091 0.0036 115 mesh
106 um No. 140 0.106 0.0041 0.076 0.003 150 mesh
90 um No. 170 0.09 0.0035 0.064 0.0025 170 mesh
75 um No. 200 0.075 0.0029 0.053 0.0021 200 mesh
63 um No. 230 0.063 0.0025 0.044 0.0017 250 mesh
53 um No. 270 0.053 0.0021 0.037 0.0015 270 mesh
45 um No 325 0.045 0.0017 0.03 0.012 325 mesh
38 um No. 400 0.038 0.0015 0.025 0.001 400 mesh
 

(a) These standard designations correspond to the values for test sieve apertures recommended by the International Standards Organization Geneva, Switzerland.

(b) These sieves are not in the fourth root of 2 Series, but they have been included because they are in common usage.

(c) These numbers (3 1/2 to 400) are the approximate number of openings per linear inch but it is preferred that the sieve be identified by the standard designation in millimeters or um.



TYLER STANDARD SCREEN SCALE SIEVES
Tyler Standard
Scale		 Closer
Sizing
Ratio 		Mesh
Designation		 USA Sieve Series
Equivalents
Opening
in Inches		 Opening
In inches		   Standard
Designation		 Alternate
Designation
1.05 1.05   26.5 mm 1.06 in.
  0.883   22.4 mm 7/8 in.
0.742 0.742   19.0 mm 3/4 in.
  0.624   16.0 mm 5/8 in.
0.525 0.525   13.2 mm .530 in.
  0.441   11.2 mm 7/16 in.
0.371 0.371   9.5 mm 3/8 in.
  0.312 2.5 8.0 mm 5/16 in.
0.263 0.263 3 6.7 mm .265 in.
  0.221 3.5 5.6 mm No. 3 1/2
0.185 0.185 4 4.75 mm No. 4
  0.156 5 4.00 mm No. 5
0.131 0.131 6 3.35 mm No. 6
  0.11 7 2.80 mm No. 7
0.093 0.093 8 2.36 mm No. 8
  0.078 9 2.00 mm No. 10
0.065 0.065 10 1.70 mm No. 12
  0.055 12 1.40 mm No. 14
0.046 0.046 14 1.18 mm No. 16
  0.039 16 1.00 mm No. 18
0.0328 0.0328 20 850 um No. 20
  0.0276 24 710 um No. 25
0.0232 0.0232 28 600 um No. 30
  0.0195 32 500 um No. 35
0.0164 0.0164 35 425 um No. 40
  0.0138 42 355 um No. 45
0.0116 0.0116 48 300 um No. 50
  0.0097 60 250 um No. 60
0.0082 0.0082 65 212 um No. 70
  0.0069 80 180 um No. 80
0.0058 0.0058 100 150 um No. 100
  0.0049 115 125 um No. 120
0.0041 0.0041 150 106 um No. 140
  0.0035 170 90 um No. 170
0.0029 0.0029 200 75 um No. 200
  0.0024 250 63 um No. 230
0.0021 0.0021 270 53 um No. 270
  0.0017 325 45 um No. 235
0.0015 0.0015 400 38 um No. 400
 

In the table of the Tyler Standard Screen Scale Sieve Series both the square root of two Series as well as the expanded series for closer sizing according to the fourth root of two as shown.

 

2. Useful Links

A. Materials Safety Data Sheet (MSDS):
    1. ChemQuik Safety Data- 500,000 MSDS files on most commonly used chemicals

      2. (Stanford Materials' Favorite)
    2. MSDS Database at Cornell University

      3. (Stanford Materials' Favorite)
    3. Where to find MSDS on the INTERNET
    4. Saferty Information on the INTERNET
    5. Chemical Safety Data
    6. ChemFinder MSDS Archives
    7. MSDS Data at Oxford University
    8. MSDS Online
    9. MSDS Safety Line- Global MSDS databases from Australia
    10. Material Safety Data Sheets from US Dept. of Labor
    11. Chemical Safety Portfolio-Hazardous properties of materials
    12. Chemical Abstract Service - 18 million substance records
    13. MSDS- Pyrotechnic Chemicals
    14. ChemTrec - A significant source for hazardous materials
    15. - OSHA Regulations and Standards
    16. Dictionary of MSDS Terms - An A to Z list of the technical words most commonly found in MSDS forms

      17. (Stanford Materials' Favorite)

B. Information sources of materials:
    1. Periodic Table of the Elements:
    2. Periodic Table on the Internet

C. Other suppliers of chemicals and materials:
    1. Alfa Aesar: Research Chemicals, Metals and Materials
    2. Aldrich Chemical Company
    3. STIGMA LTD
    4. Cerac Incorporated
    5. Atlantic Equipment Engineers
    6. AllChem Industries, Inc.

D. Materials related organizations:
    1. ASM International
    2. Welcome to AMM Online
    3. Chemical Abstracts Service
    4. London Metal Exchange

E. Some US Government's web sites:
    1. United States Patent and Trademark Office
    2. U.S. Bureau of Mines Home Page
    3. International Trade Administration
    4. U.S. Geological Survey

F. Rare earth information sources:
    1. Elements: Rare Earths, Specialty Metals & Applied Technology
    2. Rare-earth Information Center
    3. Australian Rare Earth Newsletter:

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