Vertical crusher is the core equipment for fine crushing in fracturing sand
(quartz sand/ceramic sand), responsible for processing raw materials into
particles with a mesh size of 20-70 that meet the fracturing requirements
(particle roundness ≥ 0.8, over crushing rate ≤ 5%), directly affecting the
diversion capacity of fracturing construction. If there is a difference in
particle size (needle like content exceeding 15%) or severe over crushing (-200
mesh fine powder accounting for over 8%), it will lead to a decrease in product
qualification rate and raw material utilization rate. Based on the high hardness
and strict requirements for particle size of fracturing sand raw materials, a
three-step investigation method is summarized to quickly restore the crushing
performance.
Step 1: Optimize the structure of the crushing chamber and the configuration
of the hammer head - the core components determine the particle shape
Improper crushing chamber shape, hammer head material, and arrangement are
the main causes of poor particle size and over crushing.
Poor adaptability of crushing chamber type: Ordinary straight wall crushing
chambers are prone to producing needle like particles, and the material impact
force is uneven, resulting in a high risk of over crushing; The wear of the
lining plate on the cavity wall exceeding 10mm can cause deformation of the
crushing space and disorder of the particle crushing path. Replace the "multi
chamber curved surface" crushing chamber and reduce excessive material impact
through graded crushing design; Select high chromium alloy lining plates
(hardness HRC ≥ 62), ensure smooth cavity walls without protrusions during
installation, and control the gap between lining plates at 3-5mm to avoid
material jamming.
Mismatch of Hammer Parameters or Materials: Hammer wear exceeds 1/3 of its
original thickness, resulting in decreased crushing impact force and difficulty
in crushing particles or irregular particle shape after crushing; The hammerhead
speed is too high (over 1800r/min), and the material is easily crushed due to
excessive impact; The material used is ordinary high manganese steel, which has
insufficient wear resistance and frequent replacement leads to particle size
fluctuations. Replace the bimetallic composite hammer head (wear-resistant layer
thickness ≥ 15mm), arrange it in a "staggered symmetrical" manner, and ensure
uniform clearance between the hammer heads; Adjust the speed to 1400-1600r/min
through a frequency converter, selecting high speed for fine-grained products
and low speed for coarse-grained products.
Step 2: Calibrate operating parameters and feed control - parameter matching
to reduce crushing
Improper settings of feed particle size, feed quantity, and grading
parameters can exacerbate crushing problems.
Excessive or uneven feed particle size: If the feed particle size exceeds
80mm (beyond the rated feed particle size of the equipment), it will cause a
sudden increase in crushing load and a deterioration of particle size; The
particle size fluctuates by more than 50mm, making it difficult to adapt the
crushing parameters and increasing the over crushing rate. Install a jaw crusher
for pre-treatment before feeding, controlling the particle size of the raw
material between 40-60mm. Install a vibrating screen for grading to ensure that
the particle size deviation of the feed is ≤ 10mm. Feed at a constant speed
through a spiral feeder to avoid concentrated impact of large materials on the
crushing chamber.
Overload of feeding amount or abnormal grading screen parameters: feeding
amount exceeds the set value (such as rated 50t/h, actual 65t/h), material
accumulates in the crushing chamber, particles cannot be fully crushed and the
particle shape is disorderly; Deviation in the mesh size of the grading sieve or
excessive rotation speed can result in misscreening of qualified particles and
over crushing. Use an electronic belt scale to control the measurement and
maintain it at 85% -90% of the rated value; Calibrate the mesh size of the
graded sieve (adapt to 20-70 mesh sieve according to the target particle size),
adjust the speed to 80-100r/min, and ensure accurate screening of qualified
particles.
Step 3: Adapt to the characteristics and pretreatment of fracturing sand -
improve the crushing quality at the source
Insufficient humidity, impurity content, and pretreatment of raw materials
can affect crushing stability.
High moisture content or impurities in raw materials: If the moisture content
exceeds 6%, the material is prone to bonding and crushing in the cavity,
resulting in particle aggregation and irregular particle shape; Mixing
impurities such as clay and sawdust can reduce crushing efficiency, and the
adhesion of impurities to the surface of particles can affect quality. Add a
drying process before crushing to reduce the moisture content of the raw
materials to below 3%; Install a impurity removal device (grid+magnetic
separation) to remove large impurities and metal foreign objects with a particle
size exceeding 60mm, ensuring that the purity of the raw materials is ≥ 98%.
Insufficient material buffering or blocked discharge channel: The raw
materials directly impact the crushing chamber, which can easily produce needle
like particles; If the material accumulation in the discharge channel exceeds
10cm, it will cause the material to be trapped in the crushing chamber, and
repeated impacts will cause over crushing. Install a buffer hopper at the feed
inlet to reduce the impact force of raw materials; Regularly clean the discharge
channel and install vibration devices (frequency 25-30Hz) to ensure smooth
discharge of materials and avoid retention.
Daily maintenance should pay attention to: checking the wear of the hammer
head and lining plate every week, and tightening the connecting bolts; Monthly
calibration of crusher speed and grading screen parameters, cleaning of residual
materials in the crushing chamber; Check the dynamic balance of the hammer head
every quarter and replace worn parts. By taking the above measures, the
roundness of fracturing sand particles can be increased to above 0.85, and the
over crushing rate can be reduced to below 3%, ensuring that the product meets
the requirements of fracturing construction. If there are still problems, it is
recommended to contact the manufacturer to optimize the crushing chamber type
and match the specific crushing requirements of the fracturing sand.