Sampling + Fire Assay (midterm prep)

Definition of Sampling

Obtaining relatively small quantity of material

Factors that affect sampling

time/equipment/money/prep/facility

three kinds of sampling plan

intrusive, statstical, protocol

what is intrusive sampling

sampling based on preference

what is stastical sampling

sampling that provides basic probability

what is protocol sampling

sampling for decision making purpose

what are the 4 methods of sampling

Random / Stratified / cluster/ systematic

Two types of error

accidental / intentional (salting)

methods of minimizing error

sample bag change and cut extra to control

what is a good sample prep procedure

small, dry, manageable sample that gives meaningful data

We want the sample to be...

homogeneous, fully representative

what temperature on drying oven is used for samples

110C for low SA, 60C for high SA

purpose of crusher

bring corase materials to smaller size

purpose of splitter

used to divide crushed main samples

purpose of pulverizer

splitted sample gets pulverized

purpose of mixing mat

homogenize pulverized samples

Purpose of screen

used to sieve powder sample

Reciving Procedure

recieving - sorting - selecting - preparing

definition of NORM

radioactive material, special sample prep required

sample prep if sample is rock/drill core/rock chip

Drying - crushing - split -pulverize - homogenize - sample

sample prep if sample is soil/sediment

dry - screen - homogenize - sample

Objectives of QA

ensuring samples are truly representative

Definition of Fire Assay

determining precious metals

are ores fusible

no

what is used to fuse ores?

various fluxes

what contains precious metal after fire assay

lead button

where does lead come from

lead oxide

how can Au or Ag can be measured?

instrumentally / gravimetically

what are the common fluxes

Sodium Carbonate, Litharge, Silica, Borax, Flour, Pottasium Nitrate

which of them are basic flux

Na2CO3, PbO

which of them are acidic

SiO2, Borax

what does 1 assay ton equates to

1AT = 29.166g

what does 1 oz troy / 1 short ton equal to

34.286 ppm

Classification of ores

Class I neutral / Class II Reducing / Class III Oxidizing

Definition of R.P / O.P

ability of 1 gram of ore to reduce/oxidize leads

process of calculating the flux amount

balance equation - Calculate oxidizng power - Calc. how much lead is reduced - find flux amout to make 28g lead

what is silicate degree

classifies the type of slag, base:acid ratio

how to find silicate degree

change the balance eqn to RO:SiO2 Form

on what degree Lead oxide turns into lead oxide

550C

what is cupellaton

Separation of Au and Ag from lead