Environmental pollution is attracting universal attention from all countries in the world and has become one of the global problems that must be solved in the survival and development of human society. Noise has become an important source of pollution, and noise control has become an important discipline. The so-called noise is a sound that makes people sound unpleasant and people don't need it. Noise is annoying, hearing damage, and hinders language communication and other necessary sounds. Long-term operation in a noisy environment can cause obstacles in the cardiovascular system, nervous system, and digestive system, and of course, affect people's work and productivity. In the production of stope, due to the high power, equipment and serious noise of the machinery and equipment, it seriously affects the production and life of the workers. It must be analyzed and controlled to promote the safe and comfortable conversion of the stope environment and protect the health of workers. And improve the reliability of the system.
1 Measurement and analysis methods of stope noise 1.1 Measurement of noise 1 Sound pressure level
The sound pressure level is expressed as: 
In the world, the sound pressure P0 that can be heard by the human ear is set to 0 dB, and the hearing range of the human ear is 0-120 dB.
2 Overall sound pressure level calculation of the sound source environment in the stope In the work environment, there are multiple noise sources. It is necessary to understand the relationship between the sound pressure level of each sound source and the overall sound pressure level. According to the principle of energy synthesis:
Let there be several sound sources at a certain point. The sound pressure levels generated at a certain point are L1,...Ln, respectively. If the sound pressure of each sound source is P1...Pn, then 3 Influence of noise on language communication of stop face
Noise has a masking effect on language communication. In order to obtain correct language and auditory information in a noisy environment, the field-noise ratio L(S/N) is usually used in the stope working face. Generally, L(S/N) is required to be larger than 10dB.
In the case of different signal-to-noise ratios in a working face of the stope, the frequency table for observing the blocking communication once and correctly listening to the other party's instructions is shown in the table below.
The fuzzy function can be used to establish the membership function of the noise factor of the stope:
Taking the sound pressure level domain U=[0,90], the unreasonable membership function can be expressed as follows:
1.3 The impact of noise on people 1 The degree of noise on people's troubles According to the literature [1], the annoying degree of a certain intensity noise:
The degree of trouble = - 4.798 + 0.1058 [dB (A)] (5)
Among them: 5 - indicates extreme trouble; 4 - indicates very trouble; 3 - indicates more trouble; 2 - indicates slight trouble; 1 - indicates no trouble;
2 The effect of noise on conversation According to the literature [1], the effect of a certain intensity noise on the conversation:
If you can't hear it (%)=-11.47+0.1989[dB(A)] (6)
2 Case analysis
According to the noise statistics of a mine environmental monitoring station for one month:
Through the analysis of the above data, the noise level of the stope environment is serious and the reliability is low. Measures must be taken to control and improve it to improve the efficiency of the stope system.
3 Noise control method The stope control should take comprehensive measures according to the actual situation to achieve better results. There are many ways to control noise. In the stope, you can control it as follows:
a. Replacement devices The equipments generated by general mining operations mainly include: rock drills , anchors, scrapers, mining vehicles, local fans, etc., and their noise intensity is in the range of 90-110db(A).
Replace the noise generating device or operation with a device or operation that reduces or eliminates noise. At present, the use of hydraulic trackless self-replacement equipment can reduce the noise of 10%-15% compared with pneumatic equipment, and the exhaust gas without oil mist can simultaneously improve the air quality under the well.
b. Improving noise sources Improving noise sources is one of the effective ways to reduce or avoid noise from sound sources. Generally, there are the following aspects:
(1) Reduce the friction between the machines. The main methods are: lubricating the machine; correctly calibrating the center, doing a good balance and magnetic balance; changing the material; improving the precision of machine manufacturing.
(2) Reduce airflow noise. In all large, noisy equipment, with a muffler, for example. A mine adopts 1K58 type local fan with BFVD type muffler. According to the measurement of field data, the noise can be reduced by 15-19dB(A).
3 Strengthen maintenance and repair parts maintenance, replace damaged parts in time, do not let parts loose to reduce noise.
C. Take personal protection In the working environment, workers need to wear ear protectors. The following table shows the protective effect of different materials on the human ear while the earpiece is equipped, and at the same time, the rotation work system is implemented to minimize the exposure time of the worker in the noise environment.
4 Conclusion By analyzing the noise of the stope, stope pointed out the current noise problems and propose specific improvement measures to improve overall system reliability, resulting in guidance for the actual production operations stope promote phosphorus ore The stope is developing in the direction of high efficiency, safety and high yield.
Why say closed cooling tower is energy saving and environmental protection equipment, more and more users are using this kind of equipment to replace the original equipment (open tower), we can through data analysis and comparison, the two energy data accounting can be obvious. Energy consumption is basically two major aspects, one is water, the other is electricity. Both are energy costs that no cooling tower can escape, unless you leave the equipment on.
First of all, look at the consumption of water. Water is generally consumed in two aspects. One is the flying overflow after spraying, and the other is the evaporation consumption of water.
Let's look at the open cooling tower, the spray water of the tower is basically between two and three percent of the overflow rate, if we according to the daily operation of 10 hours, excluding holidays, 280 days of operation. According to the actual open cooling tower flow of 6000 cubic meters per hour to calculate. 6000*2%*10*280= 336,000 tons of water, and the same closed cooling tower, its spray flying overflow is very small, because after all, the spray work is carried out in the tower, almost can be controlled in a few thousandths, we calculate according to 5 thousandths, the same is 10 hours of work, 280 days a year operation, To achieve the same cooling amplitude is basically 4,500 tons per hour of closed cooling tower is enough, then the calculation results: 4,500 *0.5%*10*280= 63,000 tons, it is not difficult to see, because of the different design structure caused by the waste of spraying water resources, more than 200,000 tons of terror. The bigger the pool of the open tower, the more wasted water, because the evaporation area increases, and the closed cooling tower has no pool, so the consumption here is zero. Judging from the price of a ton of water, just such a equipment, a year to solve the capital of hundreds of thousands of enterprises.
Let's look at the comparison of electric energy, electric energy is not different, because they are all through the same power equipment to operate the equipment, the power of the two is similar, the running time is the same, basically the energy consumption is about the same.
To sum up, for the closed cooling tower energy saving accounting can be strong to open the tower out, and, today are advocating energy conservation and environmental protection, this is the general trend, so the closed cooling tower is more and more favored by the majority of users.
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