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Economic benefit analysis report on investment in concrete recycling equipment

I. Analysis of current domestic concrete recycling technology level

with the improvement of domestic concrete production equipment and the promotion and use of commercial concrete, the treatment and use of residual concrete has also been promoted to an important position in the daily work of mixing stations. According to the investigation, the treatment methods of residual and residual concrete in the industry at present mainly include the following ways:

1. In the process of concrete production and supply, due to the inaccurate demand of the construction unit, the concrete supply exceeds the actual consumption, or the supplied concrete cannot be constructed for various reasons. After this happens, there is a lot of residual concrete, and the mixing plant generally transfers the concrete for treatment. However, under special circumstances, when the concrete cannot be transferred or there is no way to transfer, the concrete can only be sold at a low price, and can only be dumped if it cannot be resold. In the process of dumping concrete, the remaining concrete seriously pollutes the environment. If the dumping site is within the plant area, the later cleaning and handling will be time-consuming and laborious

2. The concrete mixing plant is equipped with multi-stage sedimentation tanks, and the circulating water is used for car brushing treatment. In this case, a small amount of concrete is diluted with circulating water to realize the separation of sand and cement slurry. The mixture is dumped into the sedimentation tank, and the analysis of sand and cement slurry is realized through multistage sedimentation. Although this method uses circulating water and saves water resources, the separation effect of sand and stone is poor. The cement slurry is mixed in the sand and stone, and the precipitated sand and stone cannot be reused. It can only be excavated by forklift equipment to form waste residue and dumped for treatment. This method not only pollutes the environment, but also wastes valuable mineral resources. At the same time, mechanical equipment such as forklifts will be damaged during the excavation process

3. Sand and gravel separator equipment is used in the mixing plant, and the remaining concrete is separated by separator. Using this method, the sand and stone in the remaining concrete can be completely separated from the cement slurry. The separated sand and stone that does not coincide with the main needle can be reused as raw materials in concrete production, saving resources. However, after the separation of sand and gravel by this method, the cement slurry still needs sedimentation treatment and cannot be reused. The formed sewage contains a large number of suspended particles, which may block the drainage system of the mixing plant after long-term accumulation. At the same time, in order to ensure the sedimentation effect, the settled cement slurry needs to be regularly dug out from the sedimentation tank, and the dug cement slurry will cause strong pollution to the environment

II. Construction conditions and process description of the recycling station project

1. Construction conditions of the recycling station:

Central Siyuanqiao mixing station and Baiziwan mixing station. At present, there are two circulating brush basins in the station. The position of the circulating brush basin is about 30 meters away from the mixing unit, which can be used as a standby site for the construction of concrete recycling station. At present, the car brushing tank has the function of sedimentation tank, which can be used. After simple transformation, the cement slurry sedimentation tank can be used as a cement slurry mixing tank in the concrete recycling station

2. Description of the process flow of the recycling station:

before the concrete recycling station, the mixer truck is cleaned with the mixing circulating water of the concrete recycling station. After cleaning, the mixture in the tank is unloaded into the recycling station separation screw for sand and stone separation. The cement slurry enters the storage tank with agitator, and the agitator will automatically stir regularly to prevent the cement slurry from settling. After the water level in the storage tank drops to the set position, the system will automatically add fresh water to the tank. The recycling station uses a pipeline transfer pump to automatically transfer the recovered water to the transfer storage tank of the mixing plant. The transfer storage tank also uses a mixer to mix regularly through the automatic system. The transfer hopper is used to transfer the recycled water to the batching scale of the mixing plant, and the automatic batching control is realized by the mixer control system

III. economic benefit analysis after the use of the recycling station

after the use of the concrete recycling station, the basic realization of zero emission of concrete materials. All the sand and gravel are reused after separation, and all the recycled water is reused, which not only saves energy resources, but also brings high economic benefits to the enterprise. The following income analysis and calculation of gapless ball screw in concrete recycling station assume that the historical station of production testing machine of Jinan testing machine factory uses two mixers, and the annual production of concrete is 300000 cubic meters

1. Calculation of recycled concrete amount:

a) sand and stone recycling of tank car cleaning: 40 tank cars per station, each tank car is cleaned twice a day, calculated according to the tank car loading capacity of 7m3, residual volume of 2%, 330 working days per year

concrete can be recycled by cleaning mixer trucks throughout the year 40x2x7x2%x330=3696m3

b) mixer cleaning and recycling: two mixers in each station, each mixer is cleaned four times a day, based on the mixer capacity of 2m3, the residual amount of 2%, 330 working days a year

the mixer can be cleaned all year round to recycle concrete 2x4x2x2%x330=105.6m3

c) recycle the residual concrete on the construction site: due to the construction site or other reasons, 3m3 concrete per day is returned to the mixing plant in the concrete supply, which cannot be transferred or reused, and needs to be recycled. The concrete returned from the construction site can be recycled throughout the year 3x330=990m3

the total amount of recycled concrete in the above three items: 4791.6m3

2. Calculation of material recovery in recycled concrete:

a) sand recovery: calculated by 0.8 tons of recovered sand per cubic meter of recycled concrete, the annual recoverable sand is 0.8x4791.6=3833.28 tons. According to the price of sand in the material of 42 yuan/ton, the annual recovery of sand can save material costs of 42x3833.28 = 16099776 yuan, that is, 161000 yuan

b) stone recovery: calculated by 1 ton of recovered sand per cubic meter of recycled concrete, the annual recoverable stone is 1x4791.6=4791.6 tons. Based on the price of sand in the material of 32 yuan/ton, the annual recovery of sand can save the material cost of 32x4791.6=153331.2 yuan, that is, 153000 yuan

c) amount of recycled cement slurry: calculated by 305 net weight of recycled cement slurry per cubic meter of recycled concrete and 0 kg after sample fracture, the annual recoverable cement slurry is 0.3x4791.6=1149.98 tons. After the cement slurry is diluted, it is used as recycled water. The water contains cement slurry components, which can reduce the use of fly ash and other admixtures in the mixing mix proportion. Calculated by reducing fly ash in an equal proportion, the price of fly ash material is 90 yuan/ton. The recycled cement slurry throughout the year can reduce the use of fly ash material by 1149.98 tons, and save the cost of fly ash material by 90x1149.98=103498.2 yuan, that is, 103000 yuan

3. Calculation of water resource saving:

compared with the circulating car brushing pool process, after using the concrete recycling station, all the recycled water is automatically supplied to the mixing station for concrete production and reuse through the system. There is no overflow of circulating water in the car brushing pool. The cleaning water of the mixing station every day can be completely recycled, and the water resource can be 100% recycled. According to two mixers in each mixing station, each mixer is cleaned four times a day, and the water consumption for each cleaning is 1.5m3, the whole year is 330 working days, and the unit price of tap water is 6.4 yuan/ton. The whole year can save water 2x4x1.5x330 = 3960 tons, and the water cost can be saved 25000 yuan

4. Save other expenses:

a) the mechanical dredging cost of the circulating pool is calculated as 5000 yuan every two months, and 30000 yuan can be saved every year

b) the cost of waste slag removal and transportation, which is supplied by the circulating tank brush truck, can produce 4791.6x2=9583.2 tons of concrete waste every year. Calculated at 10 yuan per ton of waste removal cost, the annual saving of waste removal cost is about 96000 yuan

c) mechanical maintenance cost. Due to the use of concrete recycling station, sand and cement slurry are completely separated. Compared with the circulating car brushing pool process, it is not necessary to use a forklift to excavate the sedimentation tank every day, so as to reduce the probability of mechanical damage caused by the forklift when the circulating car is dredging. The annual maintenance cost of this equipment is expected to be reduced by 20000 yuan

d) environmental protection punishment. Due to the use of concrete recycling station, the zero discharge of waste water and slag from the mixing station will be realized, and there will be no environmental penalties

IV. comprehensive analysis and evaluation of the project

according to the above analysis, the process of using concrete recycling station for concrete recycling and separation and recycling water to produce concrete again not only solves the problem of wastewater and waste residue generated by traditional recycling car brushing, realizes real zero discharge, but also effectively plays the role of environmental protection and resource recycling

using the concrete recycling station, the construction cost of a single machine is about 770000 yuan. After completion, at least 5000m3 of residual concrete can be recycled every year, and the annual operation cost is about 100000 yuan. Various raw materials and costs are saved by about 588000 yuan every year. It is estimated that the equipment construction investment can be recovered in about one and a half years. After the investment is recovered, the equipment can save about 500000 yuan for the center every year. (end)

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