COMMODITIES

Actlabs offers exploration techniques for specific deposit types

Bauxite

Samples are fused with lithium metaborate/tetraborate in platinum crucibles and the molten glass is cast into a glass disc in platinum plates. These glass disks are analyzed on a Panalytical Axios Advanced wavelength dispersive XRF.

OxideDetection Limit (%)
Al2O30.01
BaO0.01
CaO0.01
Cr2O30.005
Fe2O3 (T)0.01
K2O0.01
MgO0.01
MnO0.01
OxideDetection Limit (%)
Na2O0.01
P2O50.002
SiO20.01
TiO20.01
V2O50.005
ZrO­20.01
LOI0.01

Option:

Code 4F – Sulphate SO 4 by Infrared with a detection limit of 0.3%

Chromite

Since other elements are required for the metallurgical use of chromite, chromite assays usually are combined with major oxide analysis. For example, Cr/Fe ratios are very important in assigning value to chromite as well as other deleterious elements.

8-Chromite XRF
Samples are dried at 105 °C prior to LOI or fusion as laterites can easily absorb water from air. To minimize the matrix effects of the samples, the heavy absorber fusion technique of Norrish and Hutton (1969, Geochim. Cosmochim. Acta, volume 33, pp. 431-453) is used for major element (oxide) analysis. Prior to fusion, the loss on ignition (LOI), which includes H2O+, CO2, S and other volatiles, is determined from the weight loss after roasting the sample at 1050°C for 2 hours. The fusion disk is made by mixing a 0.5 g equivalent of the roasted sample with 6.5 g of a combination of lithium metaborate and lithium tetraborate with lithium bromide as a releasing agent. Samples are fused in Pt crucibles using an automated crucible fluxer and automatically poured into Pt molds for casting. Samples are analyzed on a Panalytical Axios Advanced wavelength dispersive XRF.

The intensities are then measured and the concentrations are calculated against the Ausmon standard which adjusts the calibration. Control standards are run to verify the procedure. Matrix corrections are done by using the oxide alpha – influence coefficients provided also by Norrish and Hutton (1969). In general, the limit of detection is about 0.01 wt% for most of the elements.

8-Chromite Oxides and Detection Limits (%)

OxideDetection Limit (%)
Al2O30.01
CaO0.01
Co3O40.01
Cr2O30.01
CuO0.01
Fe2O30.01
K2O0.01
MgO0.01
MnO0.01
Na2O0.01
NiO0.01
P2O50.01
SiO20.01
TiO20.01
V2O50.01
LOI0.01

Options:

1C-OES for Au, Pt, Pd

Coal

ParameterASTM Method
Sample PreparationD2013
Dry Screen Analysis (1 kg) (first fraction)D4749
Specific Gravity (Relative Density)D167
Total Moisture (TM)D3302
Proximate Analysis (Ash, Inherent Moisture, Volatile Matter)D3172
Free Swelling IndexD720
Calorific Value (CV)D5865
Total SulphurD 4239
Forms of Sulphur (including sulphates, pyritic sulphur and organic S)D2492
MercuryD3684
Equilibrium MoistureD1412
Ash Fusion Temperature (Reducing, Oxidizing, Combined)D1857
Ultimate Analysis:  
Carbon Hydrogen
Carbon Carbon
Nitrogen
D3176
NitrogenD5373
Bulk Density
F in coal
Cl in coal
Loss on Ignition 750 °CASTM D7348
Hardgrove GrindabilityASTM D409/D409 M-09

FUS-ICP + ICP-MS

A lithium metaborate/tetraborate fusion ICP whole rock analysis. A fused sample is diluted and analyzed by Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP-MS. Three blanks and five controls (three before sample group and two after) are analyzed per group of samples. Duplicates are fused and analyzed every 15 samples. Instrument is recalibrated every 40 samples.

INAA

A 1-30 g sample is analyzed by INAA. INAA is an analytical technique dependent on measuring gamma radiation induced in the sample by irradiation with neutrons. The primary source of neutrons for irradiation is usually a nuclear reactor. Each activated element emits a “fingerprint” of gamma radiation which can be measured and quantified.

“Near Total” Digestion – ICP Portion

A 0.25 g sample is digested with four acids beginning with hydrofluoric, followed by a mixture of nitric and perchloric acids. This is then heated using precise programmer controlled heating in several ramping and holding cycles which takes the samples to incipient dryness. After incipient dryness is attained, samples are brought back into solution using aqua regia.

Notes:

Extraction of each element by 4-Acid Digestion is dependent on mineralogy.
+ Sulphide sulphur and soluble sulphates are extracted.

Fusion ICP

OxideDetection Limit (%)
Al 2030.01%
CaO0.01%
Fe2O30.01%
K2O0.01%
MgO0.01%
MnO0.00%
Na2O0.01%
P2O50.01%
SiO20.01%
TiO20.00%
LOI0.01%

Trace Elements and Detection Limits (ppm, except where noted)

ElementDetection LimitUpper LimitReported By
Ag0.5100ICP/MS
As0.510,000INAA
Au2 ppb30,000 ppbINAA
Ba2500,000ICP 
Be1-ICP 
Bi0.42,000ICP/MS
Br0.55,000INAA
Cd0.55,000ICP 
Ce0.13,000ICP/MS
Co11,000ICP/MS
Cr5100,000INAA
Cs0.51,000ICP/MS
Cu110,000ICP 
Dy0.11,000ICP/MS
Er0.11,000ICP/MS
Eu0.051,000ICP/MS
Ga1500ICP/MS
Gd0.11,000ICP/MS
Ge1500ICP/MS
Hf0.21,000ICP/MS
Ho0.11,000ICP/MS
In0.2200ICP/MS
Ir5 ppb10,000 ppbINAA
La0.12,000ICP/MS
Lu0.011,000ICP/MS
Mo2100ICP/MS
Nb11,000ICP/MS
Nd0.12,000ICP/MS
Ni110,000ICP 
Pb55,000ICP 
Pr0.051,000ICP/MS
Rb21,000ICP/MS
S0.00%20%ICP 
Sb0.210,000INAA
Sc0.11,000INAA
Se310,000INAA
Sm0.11,000ICP/MS
Sn11,000ICP/MS
Sr210,000ICP 
Ta0.1500ICP/MS
Tb0.11,000ICP/MS
Th0.12,000ICP/MS
Tl0.11,000ICP/MS
Tm0.051,000ICP/MS
U0.11,000ICP/MS
V510,000ICP 
W11,000ICP/MS
Y110,000ICP 
Yb0.11,000ICP/MS
Zn110,000ICP 
Zr210,000ICP 

Coltan

Samples not requiring rare earths can be analyzed by fusion with lithium metaborate/tetraborate in platinum crucibles with the molten glass cast into a glass disc in platinum crucibles. These glass discs are analyzed by XRF. Generally low Ta2O5 detection limits can’t be achieved with this package and the INAA technique is recommended for tantalum.

8 – Coltan XRF

OxideDetection Limit (%)
Fe2O3 (T)0.01
Nb2O50.003
P2O50.01
Ta2O50.003
SnO20.003
ThO20.005
U3O80.005
WO30.003
Y2O30.003
ZrO20.003

INAA option

ElementDetection Limit (ppm)
Ce3
Eu0.2
La0.5
Lu0.05
Nd5
Sm0.1
Ta0.5
Th0.2
U0.5
Yb0.2

Major Oxide Option

ElementDetection Limit (%)
Al2O30.01%
CaO0.01
Cr2O30.01
Co3O40.005
CuO0.005
K2O0.01
MgO0.01
MnO0.001
Na2O0.01
NiO0.003
SiO20.01
TiO20.01
V2O50.005
LOI0.01

Copper

The sample is digested using a 4-acid digestion (nitric, perchloric, hydrofluoric and hydrochloric) with temperatures to 260°C. The leach solution is analyzed using ICP-OES.

ElementDetection LimitUpper Limit
Cu (total)0.001%30%

Cu (acid soluble) by Sulfuric Acid leach

1 gram of sample is leached in 5% H2SO4 and agitated for 1 hour. The leach solution is analyzed using AA.

Cu (acid soluble) by Citric Acid leach

1 gram of sample is placed into solution with 1M citric acid undergoing continuous agitation for 30 minutes. Leached copper present in the solution is quantified by AA.

8-Copper Oxide

8 – Copper Oxide + Secondary Sulfides

Cu (CN soluble) by Sodium Cyanide leach

1 gram of sample is leached in a 10% NaCN solution and agitated for 30 minutes. The leach solution is analyzed using AA.

Cu (Ferric Sulphate soluble) by Ferric Sulphate/H2SO4 leach

1 gram of sample is leached in a solution containing ferric ammonium sulphate dissolved in 3% H2SO4. The mixture is agitated for 1 hour and the leach solution is analyzed using AA.

The sample is leached with 5% H2SO4 for 1 hour with agitation then centrifuged and washed with DI water. The washed sample is then leached by 10% NaCN with agitation for 30 minutes and centrifuged and washed again. Lastly, the sample left in the test tube is digested using a 4-acid digestion to determine residual copper.

Graphite

Graphite packages listed are sold separately. Actlabs provides geochemical, mineralogical and metallurgical services for graphite.

Depending upon the mode of occurrence and origin, graphite is graded into three forms:

  • Flake – found in metamorphosed rocks as vein deposits
  • Crystalline (lumpy) – found as fissure filled veins
  • Cryptocrystalline (amorphous) – form in metamorphosed coal beds

Graphite occurs generally admixed with the country rocks and therefore it requires beneficiation for obtaining desired grade for various end-uses. Processes for graphite beneficiation depend upon nature and association of gangue minerals present. The common processes adopted are washing, sorting, and tabling, acid leaching and froth flotation.

The majority of graphite production is crushed and ground and then beneficiated by flotation.

Treating graphite by flotation typically requires a series of flotation cells to obtain a purer and purer concentrate. In the milling process, the incoming graphite products and concentrates can be ground before being classified (sized or screened), with the product size fractions (-100 mesh, +100 – 80mesh, +80 – 50mesh, +50mesh) separated and carbon contents determined.

Graphite Services:

  •       Specialized sample preparation to prevent sample loss
  •       Determining optimum grind
  •       Flotation testing
  •       Gravity concentration using Wilfley table
  •       Chemical up-grade
  •       Flow sheet development to produce a product of sellable grade
  •       FEG-MLA and FEG-QEMSCAN for determine flake size by in situ examination of core by SEM
  •       Identification of impurity minerals in graphite
  •       Determination of ways of upgrading graphite concentrate quality
  •       % Ash yield

8 – Graphite

OxideDetection Limit
C Graphitic (infrared)0.05
C - Total0.01
CO20.01

 Industrial Minerals

Prior to fusion, the loss on ignition (LOI), which includes H2O+, CO2, S and other volatiles, is determined from the weight loss after roasting the sample. The fusion disk is made by mixing the roasted sample with a combination of lithium metaborate and lithium tetraborate. Samples are fused in Pt crucibles using an automated crucible fluxer and automatically poured into Pt molds for casting. Samples are analyzed on a Panalytical Axios Advanced wavelength dispersive XRF.
Suitable for samples containing < 500ppm uranium.

Major oxides (%)

ElementDetection Limit
Al2O30.01%
CaO0.01%
Cr2O30.01%
Fe2O30.01%
K2O0.01%
LOI  1000°C0.01%
MgO0.01%
MnO0.01%
Na2O0.01%
P2O50.00%
SiO20.01%
TiO20.01%

Prior to fusion, the loss on ignition (LOI), which includes H2O+, CO2, S and other volatiles, is determined from the weight loss after roasting the sample. The fusion disk is made by mixing the roasted sample with a combination of lithium metaborate and lithium tetraborate. Samples are fused in Pt crucibles using an automated crucible fluxer and automatically poured into Pt molds for casting. Samples are analyzed on a Panalytical Axios Advanced wavelength dispersive XRF. Suitable for samples containing < 500ppm uranium.

Major oxides (%)

ElementDetection Limit
Al2O30.01%
CaO0.01%
Cr2O30.01%
Fe2O30.01%
K2O0.01%
LOI  1000°C0.01%
MgO0.01%
MnO0.01%
Na2O0.01%
P2O50.00%
SiO20.01%
TiO20.01%

Prepared samples are analyzed by dissolution in water at 30 °C with deionized water. KCl or Sylvite is dissolved as well as other soluble salts. K, Mg, Na and Ca salts are solubilized leaving insoluble salts (e.g. anhydrite, kieserite) as a residue which is dried and weighed.

This package includes:

  • Sample Prep
  • ICP
  • ICP/MS
  • Insoluble residue 
  • Moisture

8 Potash ICP Elements and Detection Limits (ppm)

ElementDetection Limit
Al2O30.01%
CaO0.01%
Fe2O30.01%
K2O0.01%
MgO0.01%
MnO0.01%
Na2O0.01%
P2O50.01%
TiO20.01%
Ag0.2
Ba1
Be0.2
ElementDetection Limit
Cd1
Ce1
Co1
Cr1
Cu1
Dy0.2
Er0.2
Eu0.2
Ga1
Gd1
Hf1
Ho1
ElementDetection Limit
La1
Li1
Mo1
Nb1
Nd1
Ni1
Pb1
Pr1
S10
Sc1
Sm1
Sn1
ElementDetection Limit
Sr1
Ta1
Tb1
Th1
U2
V1
W1
Y1
Yb0.1
Zn1
Zr1

Options:

Soluble Br, Cl

Soluble carbonate

Total Br-INAA

Total Cl INAA

Iron Ore

Prior to fusion, the loss on ignition (LOI), which includes H2O+, CO2, S and other volatiles, is determined from the weight loss after roasting the sample. The fusion disk is made by mixing the roasted sample with a combination of lithium metaborate and lithium tetraborate. Samples are fused in Pt crucibles using an automated crucible fluxer and automatically poured into Pt molds for casting. Samples are analyzed on a Panalytical Axios Advanced wavelength dispersive XRF.

Major oxides (%)

ElementDetection Limit
Al2O30.01
CaO0.01
Cr2O30.01
Fe2O30.01
K2O0.01
LOI 0.01
V2O50.003
MgO0.01
MnO0.01
Na2O0.01
P2O50.01
SiO20.01
TiO20.01

Options:

Metallic Fe by Titration

Total Fe by Titration

FeO by Titration

Davis Tube Magnetic Separation – Recoveries of ferromagnetic products are evaluated by Grind Size and Magnetic Field Strength (Gauss). To determine the chemical composition, the magnetic and non-magnetic recoveries can be analyzed by XRF and Lithium Metaborate Fusion. Contact us to discuss your requirements as procedures are very ore specific.

  • Sulphur
  • TGA Analysis
  • Satmagan Test

8- Davis Tube Magnetic Separation

Davis Tube electromagnetic separators create a magnetic field which is able to extract magnetic particles from pulverized ore. With this instrument the percentage of magnetic and non-magnetic material in a sample may be determined. Further chemical analysis may be performed on these fractions for more detailed information about composition.

A 30g aliquot of pulp sample is gradually added to the cylindrical glass tube which oscillates at 60 strokes per minute. As the sample progresses down the inclined tube the magnetic particles are captured by the magnetic field. Wash water flushes the non-magnetic fraction out of the tube until only the magnetic fraction remains. Both the magnetic and non-magnetic fractions are dried and weighed to determine the percentage of magnetics in each sample.

Satmagan 135 is used to measure the magnetite content of iron ore samples. The accuracy is better than 0.4%. Samples are placed in special vials supplied by the manufacturer. The vial is placed in the measuring hole of the Satmagan 135 that has been calibrated with standards of varying magnetite content. The abundance of magnetite is then determined.

Lithium

All packages listed are sold separately.

Code 8 – Lithium Ore

PackageMethodDetection Limit
Li assayPeroxide Fusion ICP0.01%
Li assay4 Acid Digestion ICP0.00%
Li assays on BrinesICP0.05 mg/L

Options:

Any of the above packages can be converted to multielement analysis. Common elements requested are K, Mg, B, Na and Ca

F assay by Code 4F – F (0.01%) by ISE

Notes:

For geochemical packages, see Code 1F2 for 4 Acid Digestion ICP or Code Ultratrace 7 for Peroxide Fusion ICP/OES + ICP/MS

The Multi-element brine package is Code 6MB

 Manganese Ore

Prior to fusion, the loss on ignition (LOI), which includes H2O+, CO2, S and other volatiles, is determined from the weight loss after roasting the sample. The fusion disk is made by mixing the roasted sample with a combination of lithium metaborate and lithium tetraborate. Samples are fused in Pt crucibles using an automated crucible fluxer and automatically poured into Pt molds for casting. Samples are analyzed on a Panalytical Axios Advanced wavelength dispersive XRF.

Major oxides (%)

ElementDetection Limit
Mn0.01
Al2O30.01
BaO0.01
CaO0.01
Cr2O30.005
Cu0.005
Fe2O30.01
K2O0.01
MgO0.01
Na2O0.01
P2O50.002
SiO20.01
TiO20.01
V2O50.005
LOI 0.01

Nickel Laterite

Prior to fusion, the loss on ignition (LOI), which includes H2O+, CO2, S and other volatiles, is determined from the weight loss after roasting the sample. The fusion disk is made by mixing the roasted sample with a combination of lithium metaborate and lithium tetraborate. Samples are fused in Pt crucibles using an automated crucible fluxer and automatically poured into Pt molds for casting. Samples are analyzed on a Panalytical Axios Advanced wavelength dispersive XRF.

Major oxides (%)

ElementDetection Limit
Al2O30.01
CaO0.01
Cr2O30.01
Co3O40.005
CuO0.005
Fe2O30.01
K2O0.01
MgO0.01
MnO0.001
Na2O0.01
NiO0.003
P2O50.01
SiO20.01
TiO20.01
V2O50.003
LOI 0.01

 Oil Shale

These analytical methods are used in exploration programs to determine the anticipated shale oil yield and to better delineate core characteristics. Each method listed is sold separately.

Sample Preparation

  • Wash, grind, homogenize 40 mesh
  • Grinding for Fischer Assay

Rock-Eval 2 Pyrolysis

  • S1 – hydrocarbons evolved at 300°C (mg/g)  
  • S2 – hydrocarbons evolved between 300 and 600°C (mg/g) heating at 25°C/min
  • S3 – organic carbon dioxide evolved at 300°C and up to 390°C (mg/g)  
  • Production Index, Hydrogen Index, and Oxygen Index and TMAX (MUST ANALYZE TOC TO OBTAIN HI AND OI)
  • Total Organic Carbon (LECO)

Rock-Eval 6 Pyrolysis   

  • Programmed pyrolysis + TOC + CO 2

Fischer Assay- ASTM D3904

  • Free water – moisture (wt%) by oven drying
  • Retort water (wt% and L/tonne)  
  • Oil yield (wt% and L/tonne)  
  • Gas yield (wt% and L/tonne)
  • Spent shale (wt%)   
  • Gas average molecular weight  
  • Oil relative density 

GC Scan

  • GC scan of shale gas to include as a minimum: H2, N2, CO, CO2, C1, C2, C3, C4, C5+

Elemental Analysis  

  • Total carbon, sulphur
  • Total organic carbon
  • Total oxygen
  • Pyritic sulfur
  • Sulfate sulfur
  • Mercury
  • Fluoride
  • Mineral Identification

Ultimate Analysis   

  • Quantitative elemental determination
  • Includes:Carbon
      Carbon + Hydrogen
      Nitrogen
      Total Sulphur

Proximate Analysis 

Ash, moisture and volatile matter (used to determine the distribution of products obtained when the coal sample is heated under specified conditions).

Free Swelling Index 

A measurement of the swelling properties of coal when heated without physical constraints.

Calorific Value

Quantity of head produced by combustion.

Ash Fusion Temperature   

  • Includes:Reducing
      Oxidizing
      Combined

Whole Rock Analysis  

A whole rock analysis is performed to provide chemical analysis of inorganic components of the rock.

Trace Metal Analysis

Near total digestion is performed and a full trace metal scan by ICP shall be conducted to include at least the following elements: Cu, Pb, Zn, Fe, W, Mo, Sn, In, Bi, Cd, Sb, F, Nb, Ta, Th, Cs, Y, As, Ag, U, and V.

Rare Earth Elements

Rare earths and rare elements are among the most difficult to analyze properly. It is essential that the sample be ground to 95% -200 mesh to ensure complete fusion of resistate minerals. This analysis uses a lithium metaborate/tetraborate fusion with subsequent analysis by ICP and ICP/MS. Mass balance is employed as an additional quality control technique and elemental totals of the oxides should be between 98 to 101%.

In certain circumstances the presence of small amounts of phosphate will have very severe consequences to Nb2O5 assays by this method with results being very low for Nb2O5. Reanalysis is required for Nb2O5 by fusion XRF. In many cases these types of deposits can contain high amounts of fluorite. This should be noted on the Request for Analysis form or F assays should be requested. This will speed up processing as mass balance won’t be achieved otherwise and a delay in returning results will ensue as samples get repeated.

IN NO CIRCUMSTANCES SHOULD AN ACID DIGESTION OF ANY TYPE BE USED TO EVALUATE THE ABOVE ELEMENTS AS THEY WILL ONLY BE PARTIAL ANALYSIS.

If samples contain >0.3% P2O5 then Nb2O5 and ZrO 2 are recommended to be replaced by fusion XRF as ICP-MS results may be very low.

Fusion ICP

OxideDetection Limit (%)
SiO20.01
Al2O30.01
Fe2O30.01
MgO0.01
MnO0.001
CaO0.01
TiO20.001
Na2O0.01
K2O0.01
P2O50.01
Loss on Ignition0.01

Trace Elements and Detection Limits (ppm)

ElementDetection LimitReported By
Ag0.5ICP/MS
As5ICP/MS
Ba3ICP
Be1ICP
Bi0.4ICP/MS
Ce0.1ICP/MS
Co1ICP/MS
Cr20ICP/MS
Cs0.5ICP/MS
Cu10ICP/MS
Dy0.1ICP/MS
Er0.1ICP/MS
Eu0.05ICP/MS
Ga1ICP/MS
Gd0.1ICP/MS
Ge1ICP/MS
Hf0.2ICP/MS
Ho0.1ICP/MS
In0.2ICP/MS
La0.1ICP/MS
Lu0.04ICP/MS
Mo2ICP/MS
Nb1ICP/MS
ElementDetection LimitReported By
Nd0.1ICP/MS
Ni20ICP/MS
Pb5ICP/MS
Pr0.05ICP/MS
Rb2ICP/MS
Sb0.5ICP/MS
Sc1ICP
Sm0.1ICP/MS
Sn1ICP/MS
Sr2ICP
Ta0.1ICP/MS
Tb0.1ICP/MS
Th0.1ICP/MS
Tl0.1ICP/MS
Tm0.05ICP/MS
U0.1ICP/MS
V5ICP
W1ICP/MS
Y2ICP
Yb0.1ICP/MS
Zn30ICP/MS
Zr4ICP

Note: Chalcophile elements are semi-quantitative. Assays are required to quantify chalcophile elements.

Options:

Code 8 – XRF Nb2O5, ZrO2 & Ta2O5 (0.003%)

Code 4F – F (0.01%) by ISE

 Uranium

*All listed packages are sold separately.

5D – U3O8 Assay DNC (0.1 ppm – 1 % U3O8)

Total Uranium can be determined by delayed neutron counting using an automated system at a nuclear reactor. The principle advantage of this is to provide very rapid and accurate assays for high volumes of samples at a very low cost. The upper limit of this technique is 1% U3O8. Results can be reported as U or as U3O8. From 1 to 10% U3O8, fusion XRF will provide the best quality results and above 10%, U3O8 titration is recommended for accuracy.

8 – U3O8 Titration (> 10% U3O8)

For samples greater than 10 % U3O8, analysis by titration is recommended.

Acid Digestions

Acid digestion using both aqua regia “partial” and 4-acid “near total” digestion with ICP/MS is also possible but uranium in resistate phases (zircon, monazite, etc.) may not be included in the assays. Hydroflouric acid is used in the digestion and some uranium may be volatilized due to combination with the HF.

8 – U3O8 Aqua Regia “Partial” Digestion by ICP-MS

0.5 grams of sample is weighed into disposable test tubes and digested with aqua regia at 95°C in a microprocessor controlled hot block for two hours. Samples are diluted volumetrically and analyzed by ICP/OES or can be analyzed by ICP/MS. This digestion may not be total as silicates and resistate minerals like zircon, monazite, xenotime are not dissolved. Calibration is achieved by using certified Canmet reference materials. Blanks and control standards are run throughout the analytical run.

8 – U3O8 4-Acid “Near Total” by ICP/MS

0.25 grams of sample is weighed into Teflon test tubes and digested with nitric-perchloric-hydrochloric-hydroflouric acids at 260 oC in a microprocessor controlled hot block for 16 hours. Samples are diluted and analyzed by analyzed by ICP/MS. This digestion may not be total as silicates and resistate minerals like zircon, monazite, xenotime may not be totally dissolved. Calibration is achieved by using certified Canmet reference materials. Blanks and control standards are run throughout the analytical run. Uranium may be partially volatile as UF6 can be formed and is volatile. We do not recommend this as a good analytical method for total U3O8.

8 – U3O8 Assay by XRF (0.005% – 10 % U3O8)

A 0.75 gram sample is roasted then fused with a combination of lithium metaborate/ tetraborate and fused in platinum crucibles. The fusion mix is poured into platinum dishes to form 40 mm glass discs. These discs are analyzed on a Panalytical Axios Advanced XRF. Uranium is calibrated using Canmet certified reference materials. Blanks and control standards are run throughout the analytical run as are preparation duplicates made from a new pulp. The analytical range is 0.05 %-10 % U. The best precision is achieved from 0.5%-10%.

Geochem V, U by XRF Pressed Pellet

Low levels of V and U can be analyzed by pressed pellet XRF.

ElementDetection Limit  (ppm)
V5 – 10,000
U5 – 10,000

5D – Peroxide Boron (>2ppm)

Analysis of B is performed by sodium peroxide fusion and ICP/MS.

Three separate analyses are performed in this package.

  • ICP-MS analysis on the partial digestion
  • ICP-OES analysis for major and minor elements on the near-total digestion
  • ICP-MS analysis for trace elements on the near-total digestion

Aqua Regia “Partial” Digestion – ICP-MS

A 0.5 g sample is digested in aqua regia at 90 °C in a microprocessor controlled digestion block for 2 hours.  Digested samples are diluted and analyzed by Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP-MS. One blank is run for every 68 samples. An in-house control is run every 33 samples. Digested standards are run every 68 samples. After every 15 samples, a digestion duplicate is analyzed. Instrument is recalibrated every 68 samples.

ICPMS1 – Aqua Regia “Partial” Digestion ICP-MS   Elements and Detection Limits (ppm) 

ElementDetection Limit
As0.01
Ag0.01
Sb0.01
Be0.01
Bi0.01
Cd0.01
Co0.01
Cs0.01
Cu0.01
Dy0.01
Er0.01
ElementDetection Limit
Eu0.01
Ga0.01
Gd0.01
Ge0.01
Hf0.01
Hg0.01
Ho0.01
Mo0.01
Nb0.01
Nd0.01
ElementDetection Limit
Pb0.02
Pb 2040.01
Pb 2060.02
Pb 2070.02
Pb 2080.02
Pr0.01
Rb0.01
Sc0.1
Se0.1
Sm0.01
Sn0.01
ElementDetection Limit
Ta0.01
Tb0.01
Te0.01
Th0.01
U0.01
V0.1
W0.1
Y0.01
Yb0.01
Zn0.1
Zr0.01

4-Acid “Near-Total” Digestion – ICP-OES Portion

A 0.25g sample is digested with four acids beginning with hydrofluoric, followed by a mixture of nitric and perchloric acids, heated using precise programmer controlled heating in several ramping and holding cycles which takes the samples to incipient dryness. After incipient dryness is attained, samples are brought back into solution using aqua regia.

With this digestion, resistate minerals are not digested and certain phases may be only partially solubilized. These phases include zircon, monazite, sphene, gahnite, chromite, cassiterite, rutile and barite. Ag greater than 100 ppm and Pb greater than 5000 ppm should be assayed as high levels may not be solubilized. Only sulphide sulfur will be solubilized.

The samples are then analyzed using a Varian ICP. QC for the digestion is 14% for each batch, 5 method reagent blanks, 10 in-house controls, 10 samples duplicates, and 8 certified reference materials. An additional 13% QC is performed as part of the instrumental analysis to ensure quality in the areas of instrumental drift.

ICPMS1 – 4-Acid “Near-Total” Digestion ICP   Elements and Detection Limits (%)

ElementDetection Limit
Al2O30.01
CaO0.01
Fe2O30.01
K2O0.002
MgO0.001
MnO0.001
Na2O0.01
P2O50.002
TiO20.001
Li1 ppm
Sr1 ppm
Zr1 ppm

4-Acid “Near-Total” Digestion – ICP-MS Portion

Additional elements are determined by ICP-MS on the multi-acid digest solution above.  The samples are diluted and analyzed on a Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP-MS. One blank is run for every 40 samples. In-house control is run every 20 samples. Digested standards are run every 80 samples. After every 15 samples, a digestion duplicate is analyzed. Instrument is recalibrated every 80 samples.

ICPMS1 – 4-Acid “Near-Total” Digestion ICP-MS   Elements and Detection Limits (ppm) 

ElementDetection Limit
Ag0.02
Ba1
Be0.1
Bi0.1
Cd0.1
Ce0.1
Cs0.1
Cr1
Co0.02
Cu0.1
Dy0.02
ElementDetection Limit
Er0.02
Eu0.02
Ga0.1
Gd0.1
Hf0.1
Ho0.02
La1
Pb0.02
Pb2040.01
Pb2060.02
ElementDetection Limit
Pb2070.02
Pb2080.02
Mo0.02
Nd0.1
Ni0.1
Nb0.1
Pr0.1
Rb0.1
Sm0.1
Sc0.1
ElementDetection Limit
Ta0.1
Tb0.02
Th0.02
Sn0.02
W0.1
U0.02
V0.1
Yb0.02
Y0.1
Zn1

The most abundant naturally occurring radioactive elements are potassium (K), uranium (U), and thorium (Th). K, eU, and eTh are determined by gamma spectrometry from daughter products of the uranium and thorium series. The method assumes that the decay series are in radioactive equilibrium. The samples are sealed and stored for a minimum of 28 days before analysis. When total U, Th, and K are determined, it is possible to determine if the samples are in equilibrium with their natural environment or if components have been leached out.

Options

A 0.2 g sample is first combusted in a resistance furnace at 550 °C in a pure oxygen environment to remove sulphide sulphur, although this is dependent on mineralogy (see 4F – Sulphide method description and below from ASTM). A catalyst is added to the sample and the temperature of the resistance furnace is increased to 1450 °C. During combustion, sulphur-bearing elements are reduced, releasing sulphur, which binds with oxygen to form SO2. Sulphur is measured as a SO2 in the infrared cell. An Eltra CS-2000 or Eltra Helios used for analysis.

According to ASTM E1915 in regards to sulphate sulphur, “In the absence of sulphide forms of sulphur, total sulphur may be used to estimate the sulphate sulphur concentration. The pyrolysis residual sulphur may be the best estimate of sulphate sulphur, in the presence of barite, alunite, jarosites, since these sulphate forms are not dissolved by sodium carbonate and in the presence of orpiment and realgar, since these sulphide minerals are soluble in sodium carbonate. The sodium carbonate sulphur loss may be the best estimate of sulphate sulphur in the presence of metal sulphide minerals other than iron, which may not be lost by pyrolysis and the absence of barite, alunite, jarosites, orpiment and realgar. ”

AnalysisMethodDetection Limit
SO4Infrared0.30%

A sample size of 5 to 50 grams can be used but the routine size is 30 g for rock pulps, soils or sediments (exploration samples). The sample is mixed with fire assay fluxes (borax, soda ash, silica, litharge) and with Ag added as a collector and the mixture is placed in a fire clay crucible. The mixture is then preheated at 850°C, intermediate 950°C and finish 1060°C with the entire fusion process lasting 60 minutes. The crucibles are then removed from the assay furnace and the molten slag (lighter material) is carefully poured from the crucible into a mould, leaving a lead button at the base of the mould. The lead button is then placed in a preheated cupel which absorbs the lead when cupelled at 950°C to recover the Ag (doré bead) + Au, Pt and Pd.

The Ag doré bead is digested in hot (95°C) HNO3 + HCl. After cooling for 2 hours the sample solution is analyzed for Au, Pt, Pd by ICP/OES using a Varian 735 ICP. The instrument is recalibrated every 45 samples. On each tray of 42 samples there are two method blanks, three sample duplicates, and 2 certified reference materials.

For vegetation ash samples a lower weight can be used but will result in elevated detection limits. Smaller sample splits are used for high chromite or sulphide samples to ensure proper fluxing and metal recoveries.

If values exceed upper limits, reanalysis by fire assay Au, Pt, Pd (Code 8) is recommended.

Code 1C-OES Elements and Detection Limits (ppb)

Element Detection LimitUpper Limit
Au230,000
Pt530,000
Pd530,000

References:

Hoffman, Eric L. and Dunn, Bernie, 2002. Sample Preparation and Bulk Analytical Methods for PGE. CIM Special Volume 54 The Geology, Geochemistry and Mineral Beneficiation of Platinum Group Elements Edited by Louis J. Cabri, pp.1-11.

Hoffman, Eric L., Clark, John R. and Yeager, James R., 1998. Gold Analysis – Fire Assaying and Alternative Methods. Explor. Mining Geology , Volume 7, Nos. 1 and 2, pp. 155-160.

Samples 0.2 g in size are fused with a combination of lithium metaborate and lithium tetraborate in an induction furnace to release the fluoride ions from the sample matrix. The fuseate is dissolved in dilute nitric acid, prior to analysis the solution is complexed and the ionic strength adjusted with an ammonium citrate buffer. The fluoride ion electrode is immersed in this solution to measure the fluoride-ion activity directly. An automated fluoride analyzer from Mandel Scientific is used for the analysis.

AnalysisMethodDetection Limit
FFUS-ISE0.01%

A 0.25 g sample is digested with four acids beginning with hydrofluoric, followed by a mixture of nitric and perchloric acids. This is then heated using precise programmer controlled heating in several ramping and holding cycles which takes the samples to incipient dryness. After incipient dryness is attained, samples are brought back into solution using aqua regia.

With this digestion, certain phases may be only partially solubilized. These phases include zircon, monazite, sphene, gahnite, chromite, cassiterite, rutile and barite. Ag greater than 100 ppm and Pb greater than 5000 ppm should be assayed as high levels may not be solubilized. Only sulphide sulfur will be solubilized.The samples are then analyzed using an Agilent 735 ICP. QC for the digestion is 14% for each batch, 5 method reagent blanks, 10 in-house controls, 10 samples duplicates, and 8 certified reference materials. An additional 13% QC is performed as part of the instrumental analysis to ensure quality in the areas of instrumental drift.

Code 1F2 – Elements and Detection Limits (ppm except where noted)

ElementDetection LimitUpper Limit
Ag0.3100
Al0.01%50%
As 35,000
Ba 71,000
Be110,000
Bi210,000
Ca0.01%70%
Cd0.32,000
Co110,000
Cr 110,000
Cu110,000
Fe 0.01%50%
ElementDetection LimitUpper Limit
Ga110,000
Hg1-
K0.01%10%
Li110,000
Mg0.01%50%
Mn1100,000
Mo110,000
Na0.01%10%
Ni110,000
P0.00%10%
Pb35,000
S+0.01%20%
ElementDetection LimitUpper Limit
Sb510,000
Sc410,000
Sr110,000
Te210,000
Ti0.01%10%
Tl510,000
U1010,000
V210,000
W510,000
Y11000
Zn110,000
Zr510,000

Notes:

Extraction of each element by 4-Acid Digestion is dependent on mineralogy.

+ Sulphide sulphur and soluble sulphates are extracted

Assays are recommended for values which exceed the upper limits.

ICP/MS

Fused samples are diluted and analyzed by Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP/MS. Fused blank is run in triplicate for every 22 samples. Controls and standards fused with samples are run after the 22 samples. Fused duplicates are run every 10 samples. Instrument is recalibrated every 44 samples.

ICP/OES

Samples are analyzed with a minimum of 10 certified reference materials for the required analytes, all prepared by sodium peroxide fusion. Every 10th sample is prepared and analyzed in duplicate; a blank is prepared every 30 samples and analyzed. Samples are analyzed using a Varian 735ES ICP and internal standards are used as part of the standard operating procedure.

Code Ultratrace-7 Elements and Detection Limits (ppm)

ElementDetection LimitUpper LimitReported By
Al0.01%25%ICP
As510,000ICP/MS
B1010,000ICP/MS
Ba310,000ICP/MS
Be35,000ICP/MS
Bi25,000ICP/MS
Ca0.01%40%ICP
Cd25,000ICP/MS
Ce0.85,000ICP/MS
Co0.25,000ICP/MS
Cr3010,000ICP/MS
Cs0.15,000ICP/MS
Cu210,000ICP/MS
Dy0.35,000ICP/MS
Er0.15,000ICP/MS
Eu0.11,000ICP/MS
Fe0.05%30%ICP
Ga0.25,000ICP/MS
Ge0.75,000ICP/MS
Gd0.15,000ICP/MS
Hf105,000ICP/MS
Ho0.21,000ICP/MS
In0.21,000ICP/MS
K0.10%25%ICP
La0.410,000ICP/MS
Li310,000ICP/MS
Mg0.01%30%ICP
Mn310,000ICP/MS
ElementDetection LimitUpper LimitReported By
Mo110,000ICP/MS
Nb2.45,000ICP/MS
Nd0.45,000ICP/MS
Ni1010,000ICP/MS
Pb0.85,000ICP/MS
Pr0.11,000ICP/MS
Rb0.45,000ICP/MS
S0.01%25%ICP
Sb25,000ICP/MS
Se0.85,000ICP/MS
Si0.01%30%ICP
Sm0.11,000ICP/MS
Sn0.510,000ICP/MS
Sr310,000ICP/MS
Ta0.210,000ICP/MS
Tb0.11,000ICP/MS
Te610,000ICP/MS
Th0.11,000ICP/MS
Ti0.01%25%ICP
Tl0.11,000ICP/MS
Tm0.11,000ICP/MS
U0.110,000ICP/MS
V510,000ICP/MS
W0.75,000ICP/MS
Y0.11,000ICP/MS
Yb0.11,000ICP/MS
Zn2510,000ICP/MS

Total uranium can be determined by delayed neutron counting using an automated Delayed Neutron Counting system at a nuclear reactor. Samples are irradiated in series for a brief period, the samples are then transferred under computer control to a delayed neutron counter which is an array of six BF3 detectors and neutrons emitted from the fissioning U-235 is thermalized and counted. The principle advantage of this technique is it provides very rapid and accurate assays of uranium for high volumes of samples at a very low cost. The upper limit of this technique is 1% U. Results can be reported as U or U3O8. From 1 to 10% fusion XRF will provide the best quality assay results and above 10% titration is recommended for accuracy.