Horizontal Continuous Mixer for Fiber Cement Slurry
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Solution Overview
Problem
Current batch mixers for producing fiber reinforced cementitious slurry mixtures face challenges such as non-continuous operation, long mixing times, fiber lumping and balling, damage to reinforcing fibers, and inefficiency with rapid setting materials, making them unsuitable for continuous panel production lines.
Innovation Solution
A horizontal continuous mixer with intermeshing self-wiping impellers and a mixing chamber design that allows for continuous blending of cementitious powders, water, and fibers, reducing mixing time to less than 60 seconds, preventing fiber damage, and maintaining uniformity, using a multi-stage mixing process with paddles and augers to achieve optimal rheological properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If batch mixers are used to produce fiber reinforced cementitious slurry, then mixing can be performed, but the operation is non-continuous and mixing time is long
Solution Approach 1:
The patent implements a continuous mixing process where cementitious powder, water, and fibers are continuously fed into a horizontal mixing chamber with rotating impellers. The system maintains continuous operation with material flowing through the mixer without batch interruptions, achieving steady-state production that eliminates the non-continuous operation problem of batch mixers while reducing mixing time to seconds.
2Stability of the object's composition
If conventional mixers are used for mixing, then fibers can be mixed with slurry, but fiber lumping and balling occurs
Solution Approach 1:
The mixing chamber is divided into multiple zones with different impeller configurations. The first zone uses a high-shear impeller to break up fiber lumps and balls, while subsequent zones use lower-shear impellers to gently mix and distribute fibers uniformly without causing damage. This segmented approach addresses fiber lumping by providing progressive mixing intensity.
Solution Approach 2:
Different regions of the mixing chamber have different mixing intensities and impeller types tailored to local requirements. The feed zone has high-shear mixing to disperse lumps, while the discharge zone has gentle mixing to maintain uniformity. This local optimization prevents fiber balling by matching mixing intensity to the local state of the material.
3Loss of time
If intensive mixing is applied to achieve uniformity, then mixing time is reduced, but damage to reinforcing fibers increases
Solution Approach 1:
The mixing process is segmented into multiple stages with progressively decreasing shear intensity. The first stage uses high-shear mixing for a short duration to achieve initial dispersion, followed by lower-shear stages that continue mixing without excessive force. This segmented approach reduces total mixing time while protecting fibers from damage that would occur in a single intensive mixing stage.
Solution Approach 2:
The continuous flow through the mixer allows for prolonged exposure to controlled, moderate mixing forces rather than brief exposure to intense forces. Material passes continuously through zones of increasing and then decreasing shear, achieving uniformity over time without the peak stresses that cause fiber damage in batch intensive mixing.
4Productivity
If batch mixing process is used, then mixing can be completed, but it is inefficient with rapid setting materials
Solution Approach 1:
The continuous mixing process allows rapid setting materials to be mixed and discharged without the time delays inherent in batch operations. Material flows continuously through the mixer, achieving uniformity in seconds and being immediately discharged for placement. This eliminates the timing conflicts that occur in batch mixing where setting begins during the mixing cycle, improving both productivity and reliability with rapid setting materials.
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
The solution enables continuous production of uniformly mixed fiber reinforced cementitious slurry with improved rheological properties, reducing fiber damage and lumping, and allowing for the use of rapid setting materials, enhancing the efficiency and consistency of fiber reinforced concrete panels.
Implementation Method 1
at least a portion of each horizontally mounted impeller within the second mixing section comprises a second plurality of mixing paddles mounted on a horizontally oriented shaft of the mixer at regular intervals and different circumferential locations, the paddles rotated about each respective horizontally oriented shaft within the horizontal mixing chamber
Implementation Method 2
wherein each horizontally mounted impeller within the upstream end feed section of the elongated mixing chamber comprises an auger, wherein the dry cementitious powder is fed into the upstream end feed section of the elongated mixing chamber and conveyed by the auger to the first mixing section
Data Source
Figure 1
Figure 2A~2F
Figure 2B~2E
AI summary
A method in which a stream (5) of dry cementitious powder from a dry powder feeder (2) passes through a dry cementitious powder inlet conduit (5a) to feed a first feed section (20) of a fiber-slurry mixer (32). An aqueous medium stream (7) passes through at least one aqueous medium stream conduit (7a) to feed a first mixing section (22) of the fiber-slurry mixer (32). A stream (34) of reinforcing fibers passes from a fiber feeder (33) through a reinforcing fibers stream conduit (34a) to feed a second mixing section (24) of the fiber-slurry mixer (32). The stream (5) of dry cementitious powder, aqueous medium stream (7), and stream (34) of reinforcing fibers combine in the fiber-slurry mixer (32) to make a stream of fiber-cement mixture (36) which discharges through a discharge conduit (36a) at a downstream end of the mixer (32).