Multiple-Stage Grinding Circuit for Ore Recovery
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Solution Overview
Problem
Conventional grinding circuits face inefficiencies in metal recovery due to over-grinding and under-grinding of ore, leading to reduced metal yield and high energy and media consumption, with existing systems producing a broad range of size fractions that include both excessively fine and coarse materials, resulting in lower recovery rates and increased costs.
Innovation Solution
A multiple-stage grinding circuit is introduced, comprising a first-stage grinding mill, separators to produce fines and coarse streams, a recovery circuit for marketable product extraction, and a third-stage stirred mill to grind the coarse stream further, optimizing grind size and reducing energy and media consumption, while retrofitting existing systems to minimize operational disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-stage grinding is used to produce fine particle size reduction, then metal recovery is improved, but energy consumption and media consumption increase significantly
Solution Approach 1:
The grinding process is divided into multiple stages with different grind sizes. The first stage produces a coarser grind (e.g., 65-105 microns) and the second stage produces a finer grind (e.g., 40-65 microns). This segmentation allows the system to achieve the same metal recovery as single-stage fine grinding but with reduced overall energy and media consumption by optimizing each stage for its specific function.
Solution Approach 2:
The invention changes the grind size parameter between stages. Instead of producing fine particles in a single stage, the system first produces coarser particles and then selectively grinds only the coarse fraction in a second stage. This parameter change optimizes energy efficiency by avoiding unnecessary grinding of material that already meets the size specification.
2Reliability
If conventional grinding produces fine particle size reduction, then metal recovery is improved, but the system produces excessive fine material that reduces efficiency
Solution Approach 1:
The first stage grinding mill intentionally produces a coarser grind than the final specification would require, creating a controlled amount of coarse material. This partial action approach allows the system to then selectively process only the coarse fraction in the second stage, avoiding the excessive fine material production that occurs when all material is ground to fine sizes in a single stage.
Solution Approach 2:
The classification device separates the coarse stream from the fine stream after the first grinding stage. By extracting and isolating only the coarse material that requires further grinding, the system avoids unnecessary processing of fine material and prevents the production of excessive fines that would occur in conventional single-stage grinding.
3Productivity
If multi-stage grinding with multiple separators is implemented, then grinding efficiency is improved, but device complexity increases
Solution Approach 1:
The grinding circuit is segmented into distinct functional blocks: a first grinding mill, a classification device with multiple separators, and a second grinding mill. This segmentation organizes the complexity into manageable stages, where each component has a specific function, making the overall system easier to operate and maintain despite the increased number of elements.
4Reliability
If target grind size is reduced to improve metal recovery, then recovery rates increase, but energy and media consumption increase
Solution Approach 1:
The invention changes the target grind size parameter between stages. The first stage targets a coarser size (e.g., 65-105 microns) and the second stage targets a finer size (e.g., 40-65 microns). This staged parameter change allows the system to achieve the fine grind necessary for high metal recovery while minimizing energy waste by only applying fine grinding to the fraction of material that actually requires it.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the amount of over-ground and under-ground materials, enhancing metal recovery rates, decreasing energy and media usage, and allowing for increased capacity without major shutdowns, by targeting a coarser grind size that reduces the loss of target minerals and lowers operational costs.
Implementation Method 1
separating, in a first stage of separating, the crushed ore material by size into a first fines stream and a first coarse stream
Implementation Method 2
grinding the crushed ore material through attrition and compressive forces at the grain size level
Implementation Method 3
grinding the crushed ore material through attrition and compressive forces at the grain size level
Data Source
AI summary
A method includes separating, in a first stage of separating, crushed ore material by size into a first fines stream and a first coarse stream; grinding the first coarse stream in a second stage of grinding; feeding the product of the second stage of grinding back to the step of separating; feeding the first fines stream from the step of separating to a recovery circuit; producing a rejected stream from the recovery circuit of crushed ore material that does not meet the target mineral size; separating, in a second stage of separating, the rejected stream from the recovery circuit into a second fines stream and a second coarse stream; grinding the second coarse stream in a third stage of grinding; and feeding the product of the third stage of grinding back to the recovery circuit.