First, the harm of cadmium
At the same time the rapid development of today's society has also had many side effects, pollution is one of the more serious problems of pollution and heavy metal pollution, human life on Earth is more serious.
Cadmium (Cd) is a heavy metal cadmium is an off-white serious harm to humans, mostly cadmium sulfide, cadmium carbonate present in the form of zinc ore in nature, but the content is very low, generally will not affect human health. Cadmium is mostly insoluble in water, density 8.64g/cm 3 , melting point 331.03 ° C, boiling point. Among the compounds, cadmium carbonate, cadmium hydroxide, and cadmium sulfide are insoluble in water, but cadmium sulfate, cadmium chloride, and cadmium nitrate are all soluble in water. Cadmium is volatile after heating and rapidly oxidizes into cadmium oxide in the air. However, after the natural environment is contaminated with cadmium, it can enter the human body through the food chain through enrichment in the living body, thereby adversely affecting the human body. So how is cadmium pollution produced?
The first discovery of cadmium was Strommel, a professor of chemistry and medicine at the University of Göttingen, Germany. In 1817, he separated brown powder from impure zinc oxide and made it co-heat with charcoal to produce cadmium. The development of modern industry has led to an increase in cadmium production year by year. Cadmium is mainly released into the environment on the way to the industrial production: Effluents lead zinc ore mining, mineral and generated during smelting; steel production and processing; cadmium plating wastewater, dyes, pesticides, paints Production and processing of glass, ceramics, and photographic materials. Plants absorb cadmium enriched in the soil, which can increase the cadmium content in crops. Aquatic animals absorb cadmium enriched in water, which can increase the cadmium content in animals.
There are two main forms of cadmium pollution in the soil: gas-type pollution and water-type pollution. The former mainly comes from industrial waste gas. Cadmium is scattered around the plant and settles with the exhaust gas, causing the cadmium content in the soil to exceed the standard seriously. It is cadmium pollution; the latter is mainly the beneficiation of lead-zinc ore and the discharge of wastewater from related industries (cadmium plating, alkaline batteries, etc.) into the nearby surface water system or groundwater, which also causes cadmium pollution. Most of the heavy metal cadmium elements present in the soil and in the various water systems eventually collect into the ocean, causing pollution to the ocean.
Cadmium is more and more harmful to the natural environment. For example, heavy metal cadmium can change the avoidance behavior of fishery resources organisms to its predators, affect the health status of fishery resources, reduce their egg production rate, hatching rate of fertilized eggs and early life. The survival rate of the stage leads to a decrease in the growth rate of the biological population of fishery resources, which in turn leads to the decline of the fishery word. Cadmium has the same effect on plants. As a non-essential element of plant growth, when cadmium enters the plant and accumulates to a certain extent, the plant will show toxic symptoms, usually growth retardation, plant dwarf, greening, yield Decline, quality decline, etc. And in the past few years, we have also discovered cadmium-containing rice, which has also sounded the alarm for us. This is only the impact on fishery resources and plant growth, and more seriously on the human body.
In 1955, a bone pain event that shocked the world occurred in the Shentongchuan basin of Japan. It was later discovered that the main cause of the pain was the long-term consumption of cadmium-contaminated river water by local residents and the consumption of cadmium-containing rice irrigated by this water, resulting in cadmium. Accumulation in the body causes kidney damage, which in turn leads to osteomalacia. Since then, cadmium pollution and prevention have begun to attract widespread attention worldwide.
In today's world, the population is still increasing, and the area of ​​arable land on land is continuously decreasing. Although modern technology can be used to increase production per unit area, it still cannot solve the increasingly serious food problem. The ocean provides a good solution to this problem, and the ocean industry has become an increasingly important source of resources such as protein for humans. The cadmium entering the ocean cannot be degraded by microorganisms, and the half-life is more than 20 years, so its pollution is an irreversible accumulation process. As mentioned above, in the cadmium-contaminated area, cadmium ions pass through the enrichment of the organism and eventually enter the top layer of the food chain - human.
How does cadmium cause harm to the human body?
Cadmium entering the human body forms cadmium-sulfur protein in the body, reaches the whole body through the blood, and selectively accumulates in the kidney and liver. In normal human blood, the cadmium content is very low, it will increase after exposure to cadmium, but will quickly return to normal after stopping contact. The combination of cadmium with protein molecules containing hydroxyl, amino and sulfhydryl groups can inhibit many enzyme systems and affect the normal function of the enzyme system in liver and kidney organs. Cadmium also damages the renal tubules, causing symptoms such as diabetes, proteinuria, and amino aciduria, and increases the output of urinary calcium and uric acid. Renal dysfunction can affect the activity of vitamin D3, hinder the growth and metabolism of bones, resulting in loose bones, atrophy, deformation, etc. Chronic cadmium poisoning may also cause anemia; acute cadmium poisoning can cause vomiting, gastrointestinal spasm, Abdominal pain, diarrhea and other symptoms. This shows that cadmium pollution is a serious injury to the human body. In reality, cadmium poisoning incidents continue to occur, especially for workers in alkaline battery production plants.
Second, the prevention of cadmium
Cadmium pollution is so serious to the society that it is necessary to stop the large-scale discharge of cadmium-containing toxic waste water into the environment, and to find ways to rectify contaminated soil or water bodies. There are three main methods for wastewater treatment, solid-liquid separation method (separation and precipitation of cadmium using sodium carbonate, sodium hydroxide, lime and sodium sulfide, and then harmless treatment of sediment) and floating separation method (mainly for low concentration cadmium) Waste water), iron oxide method (in the cadmium-containing wastewater into the appropriate ferrous sulfate, followed by alkali neutralization, aeration to form oxidized body). In seawater, the adsorption of heavy metal cadmium, etc. by large seaweed kelp also has a significant effect. At present, countries all over the world attach great importance to the research on cadmium pollution control methods, including engineering law, biological governance law, chemical law, and agricultural governance law. Although some achievements have been made, there are still theoretical and technical problems, which require more in-depth research.
How to prevent the harm caused by cadmium metal?
As early as 1993, the International Agency for Research on Cancer has classified cadmium as a human carcinogen. The United Nations Environment Program has included cadmium as a key environmental pollutant, and WHO has listed it as a priority for research on food contaminants, US toxicants and diseases. From 1997 to 2001, the Department of Management has listed cadmium as the seventh toxic substance that is harmful to human health.
However, the treatment of cadmium poisoning is very difficult, because cadmium has a half-life in the body for decades, is very stable, and there is no specific drug to eliminate cadmium in the body. Therefore, minimizing industrial pollution is the best and only way to prevent cadmium metal pollution.
A suggestion for preventing cadmium metal hazards:
1, a printer cartridge, the drum and other supplies, computers and other special waste recycling waste uniform centralized treatment.
2, the use of mercury- free and cadmium-free environmentally friendly batteries (no mercury-free cadmium batteries do not need to be recycled).
3, do not buy, do not use non-degradable lunch boxes and disposable chopsticks and other tableware.
4. Minimize the use of motor vehicles and use environmentally friendly fuels to achieve emission standards.
In order to prevent cadmium poisoning, smelting, use of cadmium and its compounds should have good ventilation and containment devices. The welding and plating process should be worn with a personal gas mask in addition to the necessary air exhausting equipment. Do not eat or smoke at the production site. The maximum allowable concentration of cadmium oxide in the production sites in China is 0.1 mg/m 3 . Also note that cadmium-plated utensils cannot store food, especially acidic foods such as vinegar.
The most feasible method is now: the state should take precautions against cadmium pollution, prevent all cadmium pollution channels, develop clean processes, and gradually phase out the production of traditional batteries; at the same time, it must also actively promote contaminated soil and water bodies. Coping with and making practical measures of governance.
Product introduction
Steel Bending Machine, one of steel reinforcement processing machinery.
The working mechanism is a horizontal working disk rotating on the vertical axis. The steel bar is placed in the dotted line position in the diagram. The supporting shaft is fixed on the machine tool.
For bending steel bars of various diameters, there are several holes on the work plate to insert the bending pin shaft, and the center pin shaft of different diameters can be replaced accordingly.
Advantages of characteristics
Applicable to all kinds of round steel, carbon steel, screw steel.
It has strong operability, high working efficiency, convenient Angle adjustment and neat bending
Operation procedures of steel bending machine:
1. Check whether the mechanical performance is good, keep the working table and bending machine surface level;
And prepare various spindle tool blocks.
2. According to the requirements of the diameter of steel bar and bending machine, the core shaft, forming shaft, iron shaft or variable structure shall be installed. The core shaft diameter shall be 2.5 times of the diameter of steel bar.
Check the core shaft, block and turntable shall be free of damage and crack, and the protective cover shall be tightly fixed and reliable, and the operation shall not be performed until it is confirmed that the air machine is running normally.
Iv. During the operation, insert the bend end of the steel bar into the clearance provided by the turntable for fixation, and fix the other end close to the fuselage and press it with your hand to check the fuselage fixation.
The side that actually holds the steel bar can be moved.
It is strictly forbidden to change the spindle, change the Angle, adjust the speed and so on.
When bending steel reinforcement, it is strictly forbidden to process steel reinforcement diameter, root number and mechanical speed beyond the mechanical specification.
When bending high hardness or low alloy steel bars, the maximum limit diameter shall be changed according to the mechanical nameplate, and the corresponding mandrel shall be replaced.
8. It is strictly forbidden to stand in the working radius of the bending steel bar and the unfixed side of the fuselage.
Curved semi - finished products should be stacked neatly, curved hooks should not face up.
When the turntable is turned, it must be done after it has stopped.
X. completion of operation, cleaning of site, maintenance of machinery, power off lock box.
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Shandong Luteng Building Equipment Co., Ltd. , https://www.lutengmachinery.com