In the quartz sand production line, the belt conveyor is the "link"
connecting crushing, sand making, screening, drying and other links, responsible
for the continuous transfer of materials. If the conveyor has problems such as
low conveying efficiency (such as capacity failing to reach the design value)
and material leakage (such as quartz sand falling down along the way), it will
not only cause waste of raw materials, increase cleaning costs, but also
interrupt the continuity of the production line and delay the overall production
schedule. As a professional manufacturer specialized in R&D and
manufacturing of quartz sand conveying equipment, we have combined the operation
and maintenance experience of hundreds of production lines to find out the core
causes and targeted solutions of low belt conveyor efficiency and material
leakage, so as to help enterprises quickly recover stable conveying.
Define the "problem determination": scientifically define the delivery
abnormality
Before troubleshooting, it is necessary to accurately judge problems through
data and phenomena to avoid blind adjustment:
Determination of low conveying efficiency: record the actual conveying
capacity of the conveyor per unit time (such as weighing the weight of quartz
sand conveyed within 1 hour with an electronic scale), and compare it with the
rated conveying capacity of the equipment (such as the rated conveying capacity
of a certain type of conveyor: 100t/h). If the actual conveying capacity is more
than 20% lower than the rated value, or the conveying time of the same material
is increased by 30% compared with the normal condition, the efficiency can be
determined as low;
Material leakage judgment: Observe whether quartz sand falls off at the feed
inlet, the middle part of the conveyor belt and the discharge outlet during the
operation of the conveyor. If the leakage amount exceeds 5kg per hour or the
leakage area exceeds 10m in length, it shall be solved mainly; At the same time,
check whether there is material residue (such as fine powder adhesion) on the
surface of the conveyor belt. Too much residue will indirectly reduce the
effective conveying capacity.
Step 1: Troubleshoot the conveyor belt and drive system - "power and carrier"
is the core
Conveyor belt is the carrier of material conveying, and the driving system
provides power for conveying. Problems of the two will directly lead to low
efficiency and leakage.
Slipping or deviation of conveyor belt
Problem performance: When the conveyor belt slips, the motor operates
normally, but the speed of the conveyor belt slows down, the conveying capacity
decreases, and the surface of the conveyor belt is heated due to friction, even
there is a sign of burnt paste; In case of deviation, the conveyor belt deviates
to one side, the edge is worn by friction with the rack, and the material spills
from the deviation side. In serious cases, the conveyor belt is clamped into the
rack and forced to stop.
Cause analysis: the slipping is mainly caused by insufficient tension of the
conveyor belt (such as the elongation of the conveyor belt after long-term use),
surface abrasion of the drive roller (friction drop), and overload of the feed
(exceeding the bearing capacity of the conveyor belt); The deviation is mainly
caused by uneven joint (uneven stress) of the conveyor belt, offset of the
roller axis (support imbalance), and improper feeding position (material
impacting one side of the conveyor belt).
Solution:
Slipping treatment: adjust the tensioning device (such as screw tensioner and
hammer tensioner), shorten the length of the conveyor belt and improve the
tension (press the middle part of the conveyor belt with hands and the
subsidence should be controlled within 10-15mm); If the drive roller surface is
worn, wrap a layer of rubber plate (increase friction force); Reduce the feed
rate to ensure that the rated belt capacity is not exceeded.
Offtracking treatment: re-calibrate the joint of the conveyor belt to ensure
that the joint is vertical to the centerline of the conveyor belt; Adjust the
idler axis, and offset the idler at the offset side by 2-3 ° to the running
direction of the conveyor belt (adjust it gradually to avoid reverse offset
caused by excessive adjustment); A distributing plate is installed at the feed
inlet to guide the materials to fall on the center of the conveyor belt and
reduce one-side impact.
The conveyor belt is worn or damaged
Problem performance: Scratch, crack or partial damage (such as tear and hole)
on the surface of the conveyor belt, leakage of fine quartz sand from the damage
and reduction of conveying capacity; If the thickness wear of the conveyor belt
exceeds 1/3 of the original thickness, the strength will be reduced, and the
tension deformation is easy to occur, further reducing the conveying
efficiency.
Cause analysis: high hardness of quartz sand (Mohs 7), abrasion caused by
long-term friction on the surface of conveyor belt; Friction between conveyor
belt and frame, roller and other parts (such as edge friction frame in case of
deviation); Hard objects such as metal blocks and stones are mixed in the
materials and pierce the conveyor belt.
Solution: replace seriously worn or damaged conveyer belt, and select
wear-resistant conveyer belt (such as PVC whole-core flame-retardant conveyer
belt, steel wire rope core conveyer belt, whose abrasion resistance is more than
50% higher than that of ordinary rubber conveyer belt); Install grating (to
intercept hard objects) and metal detector (to detect and remove metal
impurities) at the feed inlet; Regularly check the surface of the conveyor belt,
and if any minor scratch is found, fill and repair it with wear-resistant repair
agent to avoid expansion of the damage.
Step 2: analyze equipment structure and parameters - "adaptability" affects
conveying effect
If the structure and parameters of the idler layout, unloading device and
operating speed of the conveyor do not match with the characteristics of quartz
sand (particle size and water content), the efficiency and leakage will be
caused.
Improper or damaged idler layout
Problem performance: The distance between rollers is too large (such as more
than 1.5m), the conveyor belt sags seriously between two rollers, and the
materials are easy to slide and spill to both sides; The idler is damaged (such
as bearing jam and shell deformation), the conveyor belt bumps and gets stuck
during operation, the conveying speed is unstable and the efficiency is
reduced.
Cause analysis: the weight of quartz sand is not considered in the design
(for example, when conveying coarse quartz sand, the distance between rollers is
still set according to the fine powder standard); The roller is in contact with
quartz sand dust for a long time, and the bearing is worn and stuck; The carrier
roller shell is not wear-resistant (such as common cast iron carrier roller) and
is worn and deformed by quartz sand.
Solution: Relocate the carrier roller. When conveying coarse quartz sand
(>1mm), the carrier roller spacing shall be reduced to 1-1.2m to avoid
sagging of the conveyor belt; Replace the damaged carrier roller and select
wear-resistant carrier roller (such as macromolecular polyethylene carrier
roller and ceramic carrier roller, and the wear resistance is 3-5 times of that
of cast iron carrier roller); Regularly clean the dust in the roller bearing and
add lubricating grease every 3 months to extend the service life.
Unloading device failure (scraper/unloader wear)
Problem performance: A large amount of quartz sand (especially fine powder)
is left on the surface of the conveyor belt during unloading, which spills when
the conveyor belt returns; Or the gap between the discharge scraper and the
conveyor belt is too large (more than 5mm), the materials cannot be completely
scraped, and some materials are stacked under the discharge opening, affecting
the subsequent conveying.
Cause analysis: the unloading scraper rubs the conveyor belt for a long time
and causes serious wear (e.g. the edge of the rubber scraper becomes blunt); The
fixing bolts of the scraper are loose, and the adhesion to the conveyor belt is
reduced; The angle of unloader (such as electric discharge plough) is not
adjusted properly and cannot fit the surface of conveyor belt.
Solution: replace the worn unloading scraper, and select polyurethane scraper
(wear-resistant than rubber scraper, with good flexibility and high fitness);
Fasten the fixing bolts of the scraper and adjust the gap between the scraper
and the conveyor belt to 1-3mm to ensure that the materials can be discharged
completely without scratching the conveyor belt; If the unloading plough is
used, adjust the angle of the unloading plough (including the angle of 30-45 °
with the surface of the conveyor belt), and regularly check the abrasion of the
plow head and replace it in time.
The conveying speed is too fast or too slow
Problem performance: when the speed is too fast, the materials are easy to
leak due to inertia (especially fine quartz sand) at the acceleration section of
the conveyor belt, and the impact force of materials is large during unloading,
which is easy to splash out from the unloading port; When the speed is too slow,
the conveying capacity per unit time decreases, the efficiency is low, and the
materials are easy to accumulate on the surface of the conveyor belt (such as
caking accumulation when the water content is slightly high).
Troubleshooting method: measure the rotating speed of the drive roller with a
tachometer, calculate the actual conveying speed (speed=π × roller diameter ×
rotating speed) based on the diameter of the conveyor belt, and compare it with
the adaptive speed recommended in the equipment specification (for example, the
speed is generally 2-3m/s when conveying quartz sand).
Solution: adjust the parameters of motor frequency converter and adjust the
conveying speed to the suitable range - when conveying fine quartz sand
(<0.5mm), control the speed at 2-2.5m/s to reduce leakage; When transporting
coarse-grained quartz sand (>1mm), the speed can be increased to 2.5-3m/s to
improve the efficiency; Observe the conveying state of materials after
adjustment to ensure no leakage and the efficiency meets the standard.
Step 3: Adapt material characteristics - "raw material conditions" restrict
conveying effect
The particle size, moisture content and impurity content of quartz sand will
directly affect the conveying stability of the conveyor belt. If the material
characteristics are not matched with the equipment, it is easy to cause
efficiency and leakage problems.
Material moisture content is too high or caking
Problem performance: Quartz sand with water content more than 8% is easy to
adhere to the surface of the conveyor belt, leaving a lot of residues during
unloading and serious leakage; If the materials are caked (such as not fully
dewatered after ore washing), the blocky materials are easy to roll and leak
during the conveying process, and may be stuck between the roller and the
conveyor belt, causing the conveyor belt to deviate.
Solution: add drying or pre-dewatering process (such as vibrating dewatering
screen) before conveying to reduce the moisture content of materials to below
5%; If dewatering is not possible, an anti-stick coating (such as PTFE coating)
shall be applied to the surface of the conveyor belt to reduce material
adhesion; A dispersing device (such as high-speed rotating dispersing teeth) is
installed at the feed inlet to crush the caked materials and avoid rolling and
leaking during conveying.
Material particle size difference is too large or contains impurities
Problem performance: fine particles (<0.1mm) and coarse particles
(>2mm) are mixed and transported, fine powder is easy to be blown up by air
flow for leakage, and coarse particles are easy to slide for leakage due to
unstable center of gravity; Impurities such as metal blocks and stones mixed in
the materials will not only damage the conveyor belt, but also lead to blockage
of impurities, affecting the running speed of the conveyor belt and reducing the
efficiency.
Solution: add a grading process (such as vibrating screen) before conveying,
divide the quartz sand into fine and coarse particle sizes according to the
particle size, and use different conveyor belts for conveying; Gratings (to
intercept large particles of impurities) and metal detectors (to detect and
remove metal blocks) are installed at the feed inlet to ensure that the
materials entering the conveyor are free of impurities; For fine quartz sand,
dust cover can be installed above the conveyor belt to reduce the fine powder
leakage caused by air flow.
Step 4: Inspection, maintenance and operation - "management after tomorrow"
affects equipment performance
Improper daily maintenance and operation will gradually reduce the
performance of the conveyor and aggravate the problems of low efficiency and
leakage.
Equipment maintenance missing (aged parts not replaced)
Problem performance: the spring of the tensioning device is aging (elastic
force drops), resulting in insufficient tension of the conveyor belt and
slipping; The roller bearing is blocked due to lack of oil, the running
resistance of the conveyor belt increases and the speed slows down; The bolts of
the rack are loose, and the rack shakes when the conveyor belt is running, which
intensifies the deviation and leakage.
Solution: establish the "weekly maintenance" system, check the elastic force
of the spring of the tensioning device (replace it if the elastic force drops by
more than 30%), the lubrication of the roller bearing (add lithium base grease
every 3 months), and the tightening state of the frame bolts (tighten in time in
case of looseness); The conveyor shall be overhauled every half a year and the
aged parts (such as spring and bearing) shall be replaced to ensure the stable
performance of the equipment.
Improper operation of operators
Problem performance: The operator randomly adjusts the conveying speed and
fails to match the proper speed according to the material characteristics; The
feed is not controlled during feeding, resulting in overload of the conveyor
belt (exceeding the rated conveying capacity); If the problems such as deviation
and leakage are not handled timely, the problem will be enlarged and the
efficiency will be further reduced.
Solution: Formulate the Conveyor Operation Specification, specify the
conveying speed and feeding volume (such as fine powder conveying speed of 2m/s
and feeding volume of 80t/h) corresponding to different material
characteristics, and train the operators; The operator is required to inspect
once every hour, and shut down and adjust in time in case of deviation, leakage
and other problems to avoid problem expansion; The feed monitoring device is
installed to automatically alarm when the feed exceeds the rated value to remind
the operator to reduce the feed.
Preventive measures: 4. Guarantee stable and efficient operation of the
conveyor
Parameter solidification and adaptation: for specific quartz sand materials,
determine the optimal conveying speed, idler spacing, tension and other
parameters through tests, and input them into the equipment control system for
solidification to avoid random adjustment;
Regular maintenance and component replacement: maintain the equipment
according to the frequency of "weekly inspection-monthly repair-annual
inspection", timely replace the worn parts (such as conveyor belt, roller and
scraper), and select wear-resistant parts to extend the service life;
Material pretreatment: before conveying, the materials shall be dried, graded
and removed to ensure that the material characteristics are suitable for the
conveyor, so as to reduce the leakage and efficiency problems from the
source;
Intelligent monitoring and early warning: install deviation sensor and slip
sensor for the conveyor. In case of deviation and slip, the conveyor will
automatically alarm and stop to avoid problem expansion; Install the conveying
capacity monitoring device to monitor the conveying efficiency in real time, and
timely find out the causes in case of decline.
As a professional manufacturer of quartz sand conveying equipment, we can
customize the belt conveyor and supporting equipment (such as roller, unloading
device and dust cover) according to the conveying distance (10-100m), production
capacity (10-500t/h) and material characteristics of customers, and provide the
whole cycle service of "design-manufacture-installation-operational
maintenance". If your conveyor has low efficiency and material leakage problems,
please contact our technical team at any time, and we will quickly solve them
through remote guidance or on-site troubleshooting; At the same time, we can
provide equipment upgrading services (such as installing intelligent monitoring
system and replacing wear-resistant parts) to help you improve conveying
stability and efficiency and reduce production loss.