Analysis of dangerous hazard factors of main safety hazards in mineral processing

1. Electrical hazard

Electrical hazards are mainly in the form of electrical sparks and electrical injuries. Electrical hazards are related to electricity. From an energy point of view, loss of control of electrical energy will cause electrical accidents. According to the form of electric energy, electrical accidents can be classified into electric shock accidents, lightning strike accidents, and electrostatic accidents.

Beneficiation plant electrical accidents mainly electric shock, electrocution accident is an accident caused by the current and other energy conversion into electric shock accident divided into clicks and electrical injuries. Electric shock is the damage caused by the current directly acting on the human body. The electric shock is the damage caused by the electric energy, mechanical energy and other forms of energy acting on the human body; the electric shock accident often occurs suddenly, causing serious consequences in a very short time. In the concentrating plant, electrical wiring, electrical equipment, etc. in the power distribution room or workshop may cause electrical damage due to leakage and other factors caused by line aging, leakage, electrostatic discharge, damage, etc.

For the risk of electrical injury, the production of the concentrator is basically mechanized. When operating the instrumentation and electrical equipment in the power distribution room, people may get an electric shock; the charged body generates a discharge arc during the work process and causes damage to the human body or equipment. The situation also exists; the discharge caused by lightning can also cause damage to the instrument or cause ignition of the ignition, resulting in fire explosion or other injury accidents caused by control failure.

2, mechanical injury

The damage of mechanical damage is essentially the abnormal work, flow or transformation of mechanical energy (kinetic energy and potential energy), resulting in contact damage to personnel. The main forms of damage to mechanical injuries are pinching, crushing, shearing, cutting, winding or entanglement, puncture or stab wounds, friction or wear, fly-out strikes, high-pressure fluid jets, collisions and drops.

The factors that cause mechanical injury (equipment) are mainly the following:

(1) Shape and surface properties: cutting elements, sharp edges, sharp corners, rough or too smooth.

(2) Relative position: the relative distance between the moving motion and the moving object is small.

(3) Quality and stability: the potential energy of components that may move under the influence of gravity.

(4) Mass and speed (acceleration): The kinetic energy of components in controlled or uncontrollable motion.

(5) Insufficient mechanical strength: fracture or collapse of parts and components.

(6) The potential energy of a spring element (spring), the potential energy of a liquid or gas under pressure or vacuum.

The basic types of mechanical damage are mainly the following:

(1) Convolution and twisting. The mechanical damage caused by the rotary motion (such as shaft parts), including the coupling, the spindle, the lead screw, etc.; the protrusions and openings on the rotating parts, such as the protruding keys on the shaft, adjusting bolts Or spokes of pin, round-wheel shaped parts (sprocket, gear, pulley), handles on the handwheel, etc., caused by the winding of human hair, accessories (such as necklaces), fat sleeves or hem under motion. hurt.

(2) Entangling and rolling. The main dangers of causing such injuries are the coordinated movement pairs, for example, between the intermeshing gears and between the gears and the racks, the clamping points of the belts and pulleys, the chain and the sprocket entering the meshing position, two opposite Entangled by the jaws between the rollers of the swivel movement; rolling caused by rolling rotating parts, such as wheels and tracks, wheels and road surfaces.

(3) Squeeze, shear and impact. What causes such damage is the component that makes a reciprocating linear motion, such as the clamping between the moving parts and the stationary part due to insufficient safety distance between the two parts in relative motion, and the collision of the linear moving parts. Linear motion has lateral motion and vertical motion.

(4) Flying out hits. Due to the release of mechanical energy such as breakage, looseness, shedding or elastic potential energy, uncontrolled objects fly or bounce out, causing harm to people. For example, the destruction of the shaft causes the pulley, flywheel, gear or other moving parts assembled on it to fall or fly out; the loose or loose bolts cause the moving parts that are fastened to fall off or fly out; the parts that are moving at high speed are broken. Broken pieces of debris; collapse of cutting waste, etc. In addition, the position of the elastic element can cause ejection. For example: breakage of springs, belts, etc.; high pressure fluid jets caused by liquid or gas levels under pressure, vacuum, etc.

(5) Cutting and scratching. The cutting edge of the cutting tool, the burr on the surface of the part, the sharp flash of the workpiece or waste, the sharp edges, sharp angles and sharp edges of the mechanical equipment; the rough surface (such as grinding wheel, blank), etc., regardless of the state of the object is moving Still static, these dangers due to shape can cause harm.

(6) Collision and scraping. The protruding and hanging parts of the mechanical structure (such as the legs of the crane, the boom, the handle of the machine tool, etc.), the parts of the long and large workpieces extending out of the machine tool, and the like. These objects can be dangerous, whether they are stationary or moving.

Mechanical damage is manifested in the contact damage of people and moving objects. Various forms of mechanical damage, mechanical damage and other non-mechanical injuries are often intertwined. In the case of hazard identification, the different states of the machine, the different manifestations of the same hazard, the connections and effects between different hazard factors, and the apparent or potentially different forms should be considered.

In the production process, the most likely place for mechanical damage in the production process is the belt conveyor, the crusher and the rotary motion of various pumps, fans and motor couplings or pulleys; various mechanical transmissions of this evaluation project, Such as pulleys, couplings, etc. are equipped with protective covers, so as long as the basic protective measures and management measures are taken, it is not illegal to operate, the possibility of injury is small, but mechanical damage is still one of the risk factors of this project.

3. Poisoning and asphyxiation

Nitric acid is used in the concentrator production process. The nitric acid is slightly yellowish liquid; it is irritating and unstable. It releases nitrogen dioxide by light or thermal decomposition. The density is 1.5027 (25 ° C), the boiling point is 83 ° C, and the freezing point is -42. °C; can be mixed with any proportion of water, while releasing a large amount of heat; aqueous nitric acid is conductive; concentrated nitric acid is a strong oxidant, can passivate aluminum , but not corroded; and organic matter, wood chips, etc. Causes combustion; concentrated nitric acid is highly corrosive, causing burns on the skin and damaging the mucous membranes and respiratory tract. A substance containing protein, in the presence of nitric acid, produces a distinct yellow substance of yellow acid.

Nitric acid has a stimulating effect on its vapour, causing irritation of the mucous membranes and upper respiratory tract. Such as tears, throat irritation, cough, accompanied by headache, dizziness, chest tightness and so on. Prolonged contact can cause tooth decay and skin contact causing burns. Oral nitric acid causes severe pain in the upper digestive tract, burning and ulceration; severe cases may have gastric perforation, peritonitis, throat, kidney damage, shock and even suffocation.

4, lifting damage

Lifting damage refers to personal injury and equipment loss caused by equipment failure or personnel operation during the use of lifting equipment.

Lifting damage type:

(1) Lost accidents: Lost accidents include falling objects such as hanging bags, spreaders, sheet blanks, and tools. Causes of the accident: It is common that the special clamp has the object falling off, the hanging is not fast, the lifting and landing is not stable, the lifting wire rope is broken, the lifting wire rope is unhooked, the hanging object is disordered or the binding is not strong, the spreader is damaged, and the hanging position is swung too large. , equipment defects, unstable operation, etc. Hook hanging objects fall is the most important metallurgical crane accident type.

(2) Falling accident: Falling accident refers to personal injury, which occurs mostly when falling from the body, falling off by hanging objects, falling with the conveying tool, maintenance and overhaul of high-altitude equipment, and safety inspection and climbing work. Causes of the accident: the equipment is defective, the crane's moving platform, the intermediate platform for steering, the railings and other protective devices do not meet the safety design specifications, or the construction quality is not good, the operator's spirit is not concentrated, the operation process is not confirmed enough, the crane and the crane Have no regular inspections, etc.

(3) Crushing accident: crushing accidents often occur between the spreader, the hoisting and the ground objects in the workplace; the slings turn, turn over and bruise; the slings hit the ground objects and fall over the bruises; Injury or contact with the body, etc. The common crushing is that the ground crane is crushed between the steel blank stacking, the end beam and the civil structure during the operation of the bridge crane. Causes of the accident: no contact or inaccurate contact, no command or mismanagement, dangerous behavior or in danger zone, unstable lifting and landing, unsettled sling, slanting sling, heavy hanging, unskillful operation, lifting of the cart Failure of safety protection devices such as operation, emergency stop or limit switch.

In the concentrator, the lifting equipment is used frequently, and special attention should be paid to prevention.

5, dust hazards

Dust hazard refers to the environment where the concentration of solid particles contained in the air is too large, or contains toxic and harmful solid particles, and the operator may cause damage to his body or organs during normal work. We say that there is dust hazard in this workplace.

The harm of dust damage to the human body is very serious; after inhaling production dust, the human body can stimulate the respiratory tract, causing inflammation of the upper respiratory tract such as rhinitis, pharyngitis and bronchitis, and can develop into pneumoconiosis seriously; at the same time, productive dust can stimulate The skin causes dry skin, folliculitis, pyoderma and other diseases. Such as: metal and abrasive dust can cause corneal damage, resulting in corneal sensation and corneal opacity; organic dust (such as animal dust), can cause asthma, occupational allergic pneumonia;

In the ore dressing plant, dust is generated during the transportation, crushing and crushing of the ore, fine ore belt transportation, ore sample preparation and product loading and unloading. The dust flying may be directly inhaled by the human body.

6, noise damage

Noise is a kind of sound that causes people to be irritated, or the volume is too strong and endangers human health. The noise has the following forms of damage to the human body:

(1) Strong noise can cause discomfort in the ear, such as tinnitus, earache, and hearing impairment. It has been determined that noise above 115 decibels can also cause deafness. According to clinical medical statistics, if you live in a noisy environment above 80 decibels, you can reach 50% of deafness.

(2) Reduce work efficiency. The study found that noise above 85 decibels can be distracting, people will feel noisy and therefore unable to concentrate on their work, resulting in reduced work efficiency.

(3) damage to the cardiovascular system. Noise is a risk factor for cardiovascular disease. Noise can accelerate heart aging and increase the incidence of myocardial infarction. Medical experts have shown through human and animal experiments that long-term exposure to noise can increase the secretion of adrenal glands in the body, thereby increasing blood pressure. People who live for a long time with an average of 70 decibels of noise can increase the incidence of myocardial infarction by about 30%, especially Nighttime noise can make the incidence higher.

(4) Noise can also cause disorders such as nervous system dysfunction, mental disorders, endocrine disorders, and even accidents. A noisy working environment can cause dizziness, headache, insomnia, multiple dreams, general malaise, memory loss, and fear, irritability, inferiority, and even confusion.

(5) Damage to vision caused by noise. People only know that noise affects hearing, but in fact, noise also affects vision. The test shows that when the noise intensity reaches 90 decibels, the sensitivity of human visual cells decreases, and the response time of identifying weak light is prolonged. When the noise reaches 95 decibels, 40% of the pupils are enlarged and blurred, and when the noise reaches 115 decibels, Most people's eyeballs have different degrees of adaptation to light intensity. Therefore, people who are in a noisy environment for a long time are prone to eye damage such as eye fatigue, eye pain, vertigo, and visual tears. At the same time, the noise can cause abnormalities in color vision and visual field. The survey found that noise reduced the visual field of red, blue and white by 80%.

In the production process, crushers, belt conveyors, fans, dust removal, grinding, flotation, drying and other equipment will generate strong noise, which may cause harm to the human body and may cause secondary accidents.

7, falling from a height

Falling from a height is a casualty caused by a fall in a high-altitude operation. The high-altitude operation refers to the work performed at a height where the falling height reference surface is more than 2 m (including 2 m).

The main types of fall from high places are: sudden breakage due to insufficient strength of the material to be pedaled; emptying and instability when moving at high position; collision with moving objects due to improper position or operation error when working at high places Falling and so on.

The main reason for the fall of the high place is that the operator lacks the safety technical knowledge of the high-altitude operation and the safety facilities against the fall of the high place, the equipment is not perfect, and the workers are not concentrated.

During the production process of the concentrator, the production line operators or managers sometimes need to work on the platform or belt corridor of the equipment, so there is a possibility of falling from a height.

8, drowning

The drowning is commonly called drowning, and the drowning accident is very fast. Generally, it can die due to respiratory heartbeat stop in 4 to 5 minutes or 6 to 7 minutes. The main reasons for drowning and death are as follows:

(1) A large amount of water and sediment enter the mouth, nose, trachea and lungs to block the respiratory tract and suffocate.

(2) Panic, cold, throat suffocation, airway obstruction and suffocation.

(3) Fresh water drowning, a large amount of water into the blood, blood is diluted, hemolysis occurs, and elevated blood potassium leads to ventricular fibrillation - heartbeat stops.

Performance when drowning:

(1) The lighter face is pale, the lips are blue, the fear, the consciousness is clear, and the breathing heartbeat exists.

(2) The face of the severe person is blue and swollen, the mouth is full of foam or bloody color, the upper abdomen is inflated, the limbs are cold, the coma is not awake, the convulsions, and the respiratory heartbeat have stopped.

In the production process of the concentrator, 60m tail sand thick pool, copper , iron concentrate thick pool and other staff members fall into the tank, causing drowning accidents. Therefore, as long as basic protective measures and management measures are taken, it is not illegal to operate. The possibility is small, but drowning damage is still one of the risk factors of this project.

9, other injuries

The concentrator may also have other damages such as raw material transportation, unloading process and driving vehicles during the production process.

Butt welding flange is a kind of pipe fittings, which refers to the flange with neck and transition from pipe to butt welded pipe. The welding flange is not easy to be deformed, sealed well and widely used. It has the corresponding rigidity and elasticity requirements and reasonable butt welding to reduce the thin transition, the weld is far away from the joint surface, and the joint surface is free from the deformation of welding temperature.

Welding flanges are not easily deformed, sealed and widely used, with the corresponding rigidity and elasticity requirements and reasonable butt welding thinning transition, the distance between the weld and the joints is large and the joint is free from the deformation of the welding temperature. It adopts a relatively complex structure of the flex, which is suitable for high pressure or high temperature, high temperature and high pressure. And low temperature pipes are usually used for connection of pipes and valves with PN greater than 2.5MPa, and also for transporting expensive, flammable and explosive medium pipelines.

Product parameters
(1) center circle diameter of bolt hole: 50mm----2130mm
(2) the diameter of bolt hole: 11mm-30mm
(3) flange thickness: 12mm-58mm
(4) outer diameter of pipe: A (17. 2-2032MM) B (14-2020MM)
(5) flange diameter: A (18-2036MM) B (15-2024MM)
(6) flange theoretical weight: 0.36kg--234.6kg (DN1800)

Weld Neck Flange

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