Sampling Techniques in Ore Processing

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Questions and Answers

What is the purpose of sample preparation in mineral beneficiation?

To enhance the quality of the sample material

To reduce the quantity of the sample for analysis (correct)

To increase the size of the material for analysis

To combine multiple samples into one

Which method is commonly used for collecting samples from streams of solids?

Micro splitter

Paper cone splitter

Vezin sampler (correct)

Riffle splitter

What characteristic of the sampling cutter width is recommended in relation to particle size?

It should be half the top size of the particle

It should be three times the top size of the particle (correct)

It should be twice the top size of the particle

It should be equal to the top size of the particle

What types of samples are developed as part of the sampling process?

Final and gross samples Signup and view all the answers

What is the impact of particle size on the amount of sample required?

Finer materials require smaller sample sizes Signup and view all the answers

What is the role of the sampler's knowledge and judgment in sample preparation?

It is essential due to the complexity of conditions Signup and view all the answers

Which of the following sampling devices is specifically used for pulp sampling in upward flow pipes?

Poppet valves Signup and view all the answers

What aspect of sampling is directly related to the empirical definitions of particle size?

The determination of sample size required for a representative sample Signup and view all the answers

What is essential for obtaining a representative sub-sample from a gross sample?

Mixing the gross sample thoroughly before reduction Signup and view all the answers

Which of the following methods is NOT used to obtain a gross sample?

Sifting Signup and view all the answers

What are the two primary sampling methods used to obtain a gross sample?

Random sampling and Systematic sampling Signup and view all the answers

What effect does a bad sample have on test work and mill design?

It results in wastage and potentially a wrongly designed mill Signup and view all the answers

How is a gross sample initially collected from a large lot of dry material?

In stages using various sampling equipment Signup and view all the answers

Why is sampling considered a statistical technique?

It is based on the theory of probability to infer information about a whole Signup and view all the answers

What is a prerequisite for developing a satisfactory flowsheet in ore processing?

Having a fully representative ore sample Signup and view all the answers

Which type of sample represents a workable quantity for laboratory analysis?

Sub-sample Signup and view all the answers

What is the primary reason finer particles are preferred for sampling in ore analysis?

They contain more individual elements per pound. Signup and view all the answers

Which sampling method is considered most reliable when obtaining a representative sample from a process plant?

Collecting samples from a moving stream. Signup and view all the answers

What is the effect of having an uneven number of large high-grade ore particles in the sample lot?

It leads to inaccurate sampling and analysis. Signup and view all the answers

What should the ratio of the diameter of the largest particles to the weight of the sample be to ensure accuracy?

It should not exceed a safe proportion. Signup and view all the answers

Which particle size requires the minimum sample weight of 2048 pounds according to the provided table?

1.25 inches Signup and view all the answers

What is termed as an 'increment' in the sampling process?

The material collected at each sampling instance. Signup and view all the answers

What is a key factor that influences the probability of a sample being representative?

The number and size of the increments collected. Signup and view all the answers

When reducing the size of ore samples, what critical step should be performed between each cutting down of the sample?

It should be re-crushed sufficiently. Signup and view all the answers

Study Notes

Sampling

Definition: Sampling involves taking a representative portion of a large material for analysis, ensuring the proportions and distributions of examined qualities are the same in both the sample and the original material.
Purpose:
- Determine the quality of the ore entering the processing plant
- Monitor the condition of the ore during processing to optimize treatment
- Identify recovery rates and minimize losses
Importance of Representative Samples: A representative sample is critical for creating an accurate flowsheet for ore processing. A bad sample can lead to wasted testing and an incorrect mill design.
Sampling Methods:
- Dry Material: Sampling involves collecting a primary sample (gross sample) using mechanical or hand-tool samplers.
  - Random Sampling: Each part of the material has an equal chance of being selected.
  - Systematic Sampling: Samples are selected at regular intervals.
- Hand-Tool Samplers: Drill, shovel, scoop, auger, pipe, and slot samplers are commonly used.
- Sample Reduction:
  - The gross sample is reduced to a manageable size through multiple stages of sampling, resulting in secondary and ternary samples.
  - The final sample, also known as the test sample, is prepared for analysis.
- Sample Preparation Techniques:
  - Coning and Quartering: The sample is piled into a cone shape and divided into quarters.
  - Sample Splitters: Paper cone splitter, riffle splitter, rotary cone splitter, rotary table splitter, or micro splitter.
- Sampling Streams of Solids and Pulps:
  - Sample Cutters: Mechanical or manual cutters withdraw small quantities of material at predetermined frequencies and speeds.
  - Vezin Sampler: A common falling ore sampling device.
  - Poppet Valves: These are used for pulp sampling in pipes, especially where the flow is upward.
Sampling Factors:
- Size of the original material
- Particle size of the material
- Sampling method
- Purpose of the sample
Sample Size and Particle Size:
- Finer materials require smaller samples due to the higher number of individual particles per unit weight.
- Table 3.1 shows the relationship between particle size and recommended sample size.
Sample Preparation for Chemical Analysis:
- Re-crushing is necessary between sample reduction stages to ensure uniform particle size for accurate analysis.
- The ratio of the diameter of the largest particles to the weight of the sample should be within a safe proportion.
Sampling in Process Plants and Mines:
- Preferably collect samples from moving streams of material like conveyor belts, slurry pipelines, or chutes.
- Each material collection is called an increment.
- The method of collecting increments and the number of increments taken greatly influence the representativeness of the sample.

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Description

This quiz covers the fundamentals of sampling in ore processing, including methods and the significance of representative samples. Understand how proper sampling techniques impact the quality control and optimization of ore treatment processes. Test your knowledge of random and systematic sampling methods.