Pulp Lifter Gate and Grate Design for Mill Discharge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pulp lifters in grinding mills suffer from a high proportion of pebble fraction remaining in the system, which reduces volumetric capacity, increases mill mass, and can block grate openings, leading to inefficient slurry flow and potential slurry pooling.
Innovation Solution
A pulp lifter design featuring a movable gate between the collecting and discharge regions, an S-shaped curvature in the trailing edge wall, and a projection on the leading edge wall to form a pocket for pebbles, along with a grate with fewer openings near the trailing edge, facilitating earlier inward movement of slurry and pebbles and preventing their return to the collecting region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional pulp lifter design is used, then structure is simple, but pebble fraction remains in the system reducing volumetric capacity
Solution Approach 1:
The pulp lifter chamber is divided into distinct functional zones: a collecting region for slurry accumulation and a discharge region for pebble discharge. The grate is segmented with varying opening densities across different radial positions, creating zones that selectively facilitate slurry passage while retaining pebbles for controlled discharge.
Solution Approach 2:
The grate openings are non-uniformly distributed, with fewer openings near the trailing edge wall and more openings near the leading edge wall. This local variation in grate structure optimizes slurry flow characteristics and pebble discharge efficiency at different locations within the chamber.
2Productivity
If conventional pulp lifter design is used, then manufacturing is simple, but pebbles block grate openings and reduce flow efficiency
Solution Approach 1:
The grate is designed with spatially varying opening densities, having fewer openings near the trailing edge wall and more openings near the leading edge wall. This local differentiation optimizes slurry flow efficiency while maintaining manufacturability through standardized grate construction techniques.
3Weight of moving object
If conventional pulp lifter design is used, then structure is simple, but pebbles remain in the chamber increasing mill mass
Solution Approach 1:
The chamber is segmented into collecting and discharge regions with a strategically positioned gate. This segmentation enables complete pebble discharge by directing pebbles toward the discharge region while preventing their return to the collecting region, thereby minimizing residual pebble mass in the mill.
Solution Approach 2:
A movable gate is introduced that dynamically adjusts between open and closed positions based on the rotational position of the chamber. The gate closes to prevent pebble return during the discharge phase and opens to allow slurry passage during the collection phase, optimizing mass discharge efficiency.
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
Enhances the discharge efficiency of both slurry and pebbles, reducing the retention of pebbles within the pulp lifter, thereby increasing the mill's volumetric capacity and maintaining flow efficiency even at higher rotational speeds.
Implementation Method 1
the gate being movable between an open position, in which the gate permits solid material to pass from the collecting region to the discharge region, and a closed position, in which the gate prevents return movement of solid material from the discharge region to the collecting region
Implementation Method 2
a grate that allows slurry to pass to a radially outward collecting region of the pulp lifter chamber
Implementation Method 3
the trailing edge wall has an S-shaped curvature between a radially outer end and a radially inner end whereby the radial position of maximum slope of the trailing edge wall varies during rotation of the pulp lifter
Implementation Method 4
the leading edge wall is provided with a projection between a radially outer end and a radially inner end of the leading edge wall, the projection being configured to form a pocket for receiving pebbles that land on the leading edge wall during rotation of the pulp lifter
Data Source
Figure 1A~1C
Figure 2A
Figure 2B
AI summary
A pulp lifter for installation in a rotary grinding mill has a leading edge wall (4) and a trailing edge wall (2) with respect to rotation of the mill. The leading edge wall (4) and the trailing edge wall (2) define a pulp lifter chamber (1 ), and a grate allows slurry to pass to a radially outward collecting region (10) of the pulp lifter chamber for removal from the mill by way of a radially inward discharge region of the pulp lifter chamber. The pulp lifter chamber (1 ) further comprises a gate (6) positioned between the collecting region (10) and the discharge region, the gate (6) being movable between an open position, in which the gate (6) permits solid material to pass from the collecting region (10) to the discharge region, and a closed position, in which the gate (6) prevents return movement of solid material from the discharge region to the collecting region (10). Also, a pulp lifter whose trailing edge wall (2) is inclined; a pulp lifter whose trailing edge wall (2) has a S-shaped curvature; a pulp lifter that has a pocket for receiving pebbles; and a pulp lifter whose grate has openings distributed so that the area nearer the trailing edge wall (2) has fewer openings than the area nearer the leading edge wall (4).