Test method and calculation of acid absorption of lead powder

Of the 109 chemical elements, 83 are metals. Metal is an indispensable weight in human production and life

Material. According to current research, there are many kinds of heavy metals that have reproductive toxicity to humans, of which the more common four are heavy

Metals are lead, Mercury, manganese, and cadmium.

The impact on male reproduction is illustrated by the emphasis on lead. Lead was known to be used in 4200 BC.

As early as the Roman period, there was a serious pollution of lead, especially in the Roman aristocracy.

Increases the sweetness of grape juice and alcohol, and lead poisoning occurs, resulting in a general decline in fertility and poor birth rate

And ... According to a noble district, of the 101 men 19 years old, 35 are married, of whom 18 have no heirs, 10

There are only 1 child, 7 people have 2 to 3 children, and a total of 27 children; The survival rate of future generations is very low, that is,

For survival, there are also many children who are physically and intellectually underdeveloped. Therefore, it was suggested that the fall of the Roman Empire

It is related to the low fertility caused by lead poisoning in the upper strata of Rome and the significant decline in population quality.

In recent years, lead poisoning has been caused by drinking lead-contaminated shochu and taking lead-containing drugs. Like 199.

In 4 years, the villagers in a county caused 95 cases of collective lead poisoning due to drinking farmer's own brewing "sweet potato burning". Every family uses one.

A wine cap(distiller) is fired. This wine cap is made of lead added to tin by a tinsmith using a waste battery. Therefore, it contains lead.

Very high. Distillation of soju in this vessel is, of course, a lot of lead contamination. According to the analysis, the lead content in the wine is average

Up to 273 mg per litre(1 mg per litre for lead in liquor). There are 189 men who drink this kind of wine.

, 9 women. There were 95 high levels of lead in urine, of which 53 men had symptoms of lead poisoning. According to reports, somewhere

Twenty-four male married lead workers were identified, of whom one worker's wife had a congenital epileptic daughter and the other had a child

Breeding a child with congenital heart disease, it can be seen that lead has a certain effect on future generations.

Lead can directly affect the testicle of the core organ of the male reproductive system. The normal physiological function of the testicles is mainly system

Sperm production and the synthesis of androgens, either of which is impaired, affect male reproduction

The result of the function is a change in the quality and quantity of sperm. The main manifestations are a decrease in sperm number and an increase in sperm deformity rate.

The ability to add and move is weakened. The author has analyzed the semen content of 38 lead workers and found that the semen lead is flat

The mean of 3.2 Weimoer per litre is not only significantly higher than the non-contact 0.8 Weimoer per litre, but also significantly higher than the

Lead workers 'own blood lead averaged 2.3 Weimoer per litre. Indicates that lead can enter the spermatozoon through the blood-testis barrier.

Liquid, and has a certain accumulation effect. Lead can also be interspersed by blocking the regulation of the hypothalamus-pituitary-testicular axis

The response affects male reproductive function, which affects the secretion of reproductive hormones, such as significantly reducing testosterone.

Lead powder is a mixture of 60 % ~ 80 % lead oxide and 20 % ~ 40 % lead. It is one of the main raw materials used to make polar plate active substances. The quality of lead powder has a great influence on the manufacture of lead paste, the process parameters of polarizing and the electrical performance of the battery. Lead powder has scaly petals and lumpy structures.

Quality index of lead powder. The quality indicators of lead powder include the degree of oxidation, apparent density, water absorption, dispersion, and structure of lead powder, among which the apparent density and oxidation degree are the main ones. The degree of oxidation is the percentage of lead oxide in lead powder, indicating the relationship between lead oxide and lead composition. The smaller the particles of lead powder, the higher the degree of oxidation, and the degree of oxidation is a factor that affects the porosity of the polar plate. The increase in the degree of oxidation will increase the initial capacity of the battery, and vice versa. However, if the oxidation degree is too high, the negative electrode plate will crack due to the large volume contraction during drying, and the positive polar active material will easily fall off in the recharge cycle, shortening the battery life. The degree of oxidation of lead powder is generally controlled at 60 % to 80 %. The apparent density of lead powder is the apparent density of lead powder particles naturally accumulated. It is represented by g/cm3 and is a comprehensive indicator of the thickness and degree of oxidation of lead powder. The general control apparent density in production is 1.8 ~ 2.1 g/cm3. The porosity of lead powder can be calculated from the apparent density of lead powder. The water absorption rate of lead powder is the amount of water absorption of a certain amount of lead powder, usually expressed as a percentage. The water absorption ability of lead powder in the process of paste was indicated. The water absorption rate of lead powder is related to the oxidation degree and particle size of lead powder.

There are two methods of making lead powder: First, using a lead mill similar to a ball mill, lead is ground while oxidizing in the machine. This is used in most countries. The second is the crucible process, which uses jet airflow to blow the molten lead while oxidizing it. The lead powder machine is generally a roller type. When it works, the shot(block) attached to the inner wall of the rotating cylinder rotates in the rotating cylinder with the effect of centrifugal force, takes it to a certain height, and then uses gravity to drop. In addition to the high temperature and certain humidity in the air, the surface of lead, especially the deformed edges, is oxidized by air to form lead oxides. Lead oxide falls off the surface of the shot put and is ground under the action of friction and impact, so that lead powder can be obtained and the lead powder can be taken away by blowing air. The size of the delivered particles is related to the flow rate of air.

Effect of the Production Technology of Lead Powder on the Quality of Lead Powder

The impact of the lead powder production process on the quality of lead powder is as follows[ 1] ::

(1) The effect of the amount of shot put, the amount of shot put reduced, the speed of the lead powder machine increased, the friction between the shot put decreased, the lead powder particles were too large, the apparent density was high, the temperature was too low, and the degree of oxidation was also reduced. Lead powder machine is not efficient. On the contrary, the situation is reversed. Therefore, the amount of the ball should be strictly controlled.

(2) The influence of the temperature of the cylinder body, if the temperature of the cylinder body is too high to reach the melting point of lead, and the shot put is melted into a group, it can not be made into lead powder. If the temperature in the tube is too low, the oxidation effect is reduced. The temperature of the outside wall of the tube is generally controlled at 160 ~ 180 °C and adjusted up and down to 10 °C with the season.

(3) The influence of the blower, the air has the role of oxidation and adjustment of the temperature in the barrel. Large amount, high output, but the temperature of the cylinder is not easy to maintain. The volume is small, and the temperature of the cylinder is easy to rise. Air humidity also has a certain influence on the oxidation of lead powder. The air humidity blown in is large. Because water has a medium effect, the oxidation degree of lead powder is high.

(4) The influence of climatic conditions, the production of lead powder is very seasonal, the quality of lead powder varies greatly with the change of climatic conditions. In order to maintain the quality of lead powder, it is necessary to control the temperature and humidity of the air flow and the temperature of the working environment of the lead powder machine. Generally controlled air flow temperature is 15 ~ 25 °C, relative humidity is 70 % ~ 80 %, in winter, the temperature in the workplace can not be lower than 15 °C

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