SAMPLING and SAMPLE PREPARATION PPT Flashcards
STEPS in an analysis
memorisa yot
In statistics and quantitative research methodology, a ____ is a set of individuals or objects collected or selected from a statistical population by a defined procedure
Sample
In extraction industry, it is a small portion of a whole mass that accurately represents the whole mass
Sample
- The process of taking a small portion of a material such that the consistency of the portion shall be representative of the whole
- the most difficult step in an analysis and the source of greater error
- is a progressive process in which the original material is reduced in quantity to the final mass of sample convenient for analysis
SAMPLE COLLECTION
- is the PRE -REQUISITE of effective analysis
SAMPLE COLLECTION
- the most difficult step in an analysis and the source of greater error
SAMPLE COLLECTION
“If a sample is correct and sufficiently reproducible, it automatically qualifies as representative”
-(D. Francois -Bongarcon and P. Gy)
FACTORS FOR CONSIDERATION IN SAMPLING
- Uniformity of Composition of the Bulk ( Homogeneity)
SOLUTION???
“Ore which breaks into lumps of large variation of sizes are probably of different composition”
crushing the materials into fine powder and thorough mixing is desirable to obtain a true sample
CLASSIFICATIONS OF MATERIALS
_____(1)
* Liquids – water, oil, molten metals and slags
* Gases – flue gas, producer gas
Fluids
CLASSIFICATIONS OF MATERIALS
-Metals, alloys
Tough or Sectile Materials
CLASSIFICATIONS OF MATERIALS
Ores, fluxes, coal, brittle metals, alloys, etc
Brittle or Frangible Materials
GENERAL PRINCIPLES in SAMPLING
Necessary to be mixed thoroughly and withdraw any convenient portion.
Fluids
GENERAL PRINCIPLES in SAMPLING
Quantity to be taken depends upon the value and uniformity of the material and the size of the largest particles.
Fragmental Materials
“the weight taken for sample shall be proportional to the square of the diameter of the largest particle“
Prof. R.H. Richards’ (MIT) Rule
Surface Sampling
this method consist of cutting channels across the face of exposed ore and collecting the resulting chips, fragments and dust from each channel to make a sample
Channel Sampling
Surface Sampling
- a series of chips of rock is taken either in a continuous line across the exposure or at random intervals over a face.
- used for hard or uniform ores where it is difficult to cut channels
Chip Sampling
Surface Sampling
- a grab-sample of the muck pile after blasting is sometimes taken instead of a channel sample of a face. It picks pieces of rock of convenient size.
- it is very simple , quick and cheap procedure but the accuracy of this method is very low.
Muck Sampling
Surface Sampling
- a shovelful of ore or a series of pieces selected either at random or according to a pre-arranged system is taken from each car that comes from the face. This gives a fairly large samples.
Car Sampling
Surface Sampling
- usually done at established or grid points where soil/rock chips, sediments, water, mud, etc. are collected for analysis.
Geochemical Sampling
Surface sampling
is done to further determine the mining and metallurgical properties of the deposit such as:
-grade of ore;
-degree of homogeneity if mineralization;
- rock hardness and strength;
- ore and gangue mineralogy & their variations;
- grain size of mineral;
- response to ore drilling process.
Bulk Sampling
PRIME purpose of Bulk Sampling???
To confirm grade indicated by prior sample data from drill holes or workings
BASIC FLOW DIAGRAM OF BULK SAMPLING ARRANGEMENT
MEMORISA YOT
Subsurface Sampling
horizontal and vertical excavation are made to collect mineral samples located beneath the surface
Excavation of tests Pits/Trenches
Subsurface Sampling
-collection of crushed, fines and rock cores beneath the surface using a drilling equipment.
-The drilling method could be either rotary-percussive; rotary, diamond core, churn, wash boring, hammer drilling, auger, and shot drilling.
Drilling
Goal of laboratory sample preparation
to provide, without sample loss, representative aliquants that are free of laboratory contamination that will be used in laboratory analysis to determine the concentration of an analyte.
THREE STEPS INVOLVED IN PROCESSING THE SAMPLES
- Preparing Laboratory Samples
- Measuring the Samples (Defining Replicate Samples)
- Dissolving the Samples
Preparing Laboratory Sample
A solid laboratory sample is ground to decrease particle size, mixed to ensure homogeneity, and stored for various length of time before analysis begins.
Crushing
Preparing Laboratory sample
(to reduce the particle size in order to ensure homogeneity and to facilitate attack by reagents.)
Grinding
Preparing Laboratory Sample
(to obtain laboratory sample)
– Coning and Quartering
– Riffle Splitter (Mechanical Device) - consists of a series of chutes directed alternately to opposite sides. The alternating chutes divide the sample into many portions, which are then recombined into two.
Reducing Sample Size
MEASURING THE SAMPLE
The amount of the sample is expressed most often as
Weight or volume
MEASURING THE SAMPLE
____ samples are often analyzed on a dry basis and must be dried in an oven at ____ to ____ degree Celsius for ____ to ____ hr and cooled in a desiccator before weighing
Solid
105-110 degree celcius
1 to 2 hr
MEASURING THE SAMPLE
are portion of a material of approximately the same size that are carried through an analytical procedure at the same time and in the same way
Replicate Samples
DISSOLVING THE SAMPLES
used for samples containing soluble salts
Water
DISSOLVING THE sAMPLE
used for samples that will not dissolved in water such as o Non-oxidizing acids: HCl, HBr, H3PO4, dilute. H2SO4, dilute HClO4 o Oxidizing acids: hot and concentrated H2SO4, ot and concentrated HClO4, HNO3, aqua regia (mixture of HCl & HNO3) are used for stubborn samples, HF used for silicate materials.
Acids
ACIDS
Non-oxidizing acids
5 sila
HCl, HBr, H3PO4, dilute. H2SO4, dilute HClO4
ACIDS
Oxidizing acids
hot and concentrated H2SO4,
hot and concentrated HClO4, HNO3,
aqua regia (mixture of HCl & HNO3) are used for stubborn samples
ACIDS
aqua regia (mixture of ____) are used for ____ samples
HCL & HNO3
stubborn
DISSOLVING THE SAMPLES
used for organic samples that do not dissolved in water
Organic Solvents
typically used for the dissolution of most metals, oxides, sulfides, phosphates, and carbonates.
HCl and HBr
is capable of dissolving most metals, with the exception of gold and platinum
HNO3
To dissolve Gold and Platinum, a ____ volumetric mixture of HCl and HNO3 (also known as ____) can be used.
3:1
Aqua Regia
HCl and HBr digestions are typically performed with a concentration of ____% and ____%, respectively
37% and 48-65%
When using hot acids, HCl has a constant boiling composition of ____% at ____◦C
20% at 109degree celcius
HBr has a constant boiling composition of ____% at ____◦C
48%
124 degree celcius
A ____% ____ solution is often used for the dissolution of silicates
50% HF
the process of dissolving a sample in a molten solvent known as flux that has acidic, basic, or oxidizing properties. This is carried out by mixing finely ground samples with solid flux in an inert metal crucible and heating until the flux melts, at which time it becomes very reactive and dissolves the sample. After a period, the melt is cooled and dissolved in water or diluted aqueous acid.
Fusion
Eliminating Interference
In the case of a liquid suspension, ____or ____ is often performed prior to analysis to remove any solid particles.
Filtration or Centrifugation
Eliminating Interference
In the case of a solution, there are many methods available for isolating analytes, including ____, ____, or ____
Complexation, separation, or extraction
Reasons for the performance of these procedures prior to analysis:
- to remove any species that may cause interferences in the particular analysis or
- to provide a means of concentrating the analyte prior to analysis
Methods of Eliminating Interference
- Extraction
- isolation of particular components
- transference of compounds from solid/liquid to solvent/phase
Types of extraction are commonly used for analyte isolation:
____ In ____, the two phases are both liquid and are immiscible in each other (e.g., an aqueous phase and an organic phase), creating two layers with a distinct boundary.
liquid/Liquid extraction
The reaction between the two species ( interfering species with a chelating agent) forms a stable complex which cannot undergo certain chemical reactions that are essential for quantification of the analyte.
Complexation Reaction ( Masking )
Types of Extraction are commonly used for analyte isolation:
____ - the partitioning of an analyte between the liquid in which it is dissolved and a solid support. These Such extractions are typically based upon adsorption of the solute onto the solid.
Solid-Phase extraction
Precipitation reactions, an insoluble complex is selectively formed with either the interfering species or the analyte itself. Once the precipitate is formed, it can be removed and discarded in the case of an interfering species or analyzed in the case of the analyte
Separation
