In recent years, the state has promulgated a large number of regulations and systems on environmental protection and resource utilization. Environmental protection is the most important concern of major enterprises and factories. Once there are any environmental protection problems, enterprises are not only facing fines and rectification, but also likely to face such major events as shutdown of production and closure, which affect the survival of enterprises. Environmental protection awareness has been deeply embedded in the operations of major enterprises. Among the principles, resource utilization is the lifeblood of upstream raw material enterprises. Rational use of resources, saving resources and reducing pollution emissions can effectively improve the competitiveness of enterprises and achieve win-win environmental and economic benefits. Sandstone aggregate production line, as the front end of the raw material supply chain in the construction industry, its production technology and technology play a vital role.

Sandstone aggregate production line usually includes several systems: 1. crushing system, 2. semi-finished product storage system, 3. medium and fine crushing system, 4. screening system, 5. finished product storage system, 6. loading weighing system, 7. water supply and water treatment system, 8. electrical automation system, 9. spare parts and maintenance center. Following is a general introduction of three common sand aggregate production line process:

The first type of process:

It is suitable for crushing soft and low abrasive rocks, such as limestone, etc. It is a typical process of most commercial sand aggregate processing systems at present. The process is simple and the equipment configuration is few.

Bar feeder is equipped before crushing. Bar feeder has the function of uniform, stable feeding and screening. Material on bar screen enters jaw crusher to crush, which improves the production efficiency of crusher and reduces the wear of liner. According to the situation of material source, the material under bar sieve can enter the regulating stockpile together with coarse aggregate, and can also enter the desilting sieve machine for desilting. The waste of useful material can be greatly reduced and the purpose of desilting can be achieved.

Regulating stockpile is usually set before crushing. Because of the discontinuity of automobile transportation, adjusting stockpile can ensure the continuous and stable production of follow-up process in a certain period of time and improve the utilization efficiency of equipment. At the same time, when crushing temporary overhaul or treatment of oversize stones, the follow-up process is not affected much.

Medium crushing adopts counter-impact crusher, and the crushed aggregate enters the pre-screening workshop. Among them, the aggregate that meets the specifications enters the finished aggregate pile, the over-diameter aggregate enters the fine crushing workshop, and the rest enters the finished product screening workshop for screening, and the finished aggregate that meets the requirements enters the finished aggregate pile.

The second type of process:

It is suitable for crushing hard and high abrasive rocks, such as granite and quartzite. Major use of the cone crusher “lamination crushing” principle, the finished coarse aggregate through two cone crushing, get better particle shape.

Aggregate after medium crushing enters the pre-screening workshop, and fine aggregate less than 5 mm is screened out through pre-screening. All coarse aggregate enters the fine crushing workshop for crushing. Aggregate after fine crushing enters the finished product screening workshop again. Among them, aggregate that meets the specifications enters the finished product aggregate stack, over-diameter aggregate enters the fine crushing workshop, and adjusting buffer bin is set up in the fine crushing workshop when the related host or other equipment. When emergency shutdown occurs, the silo can play the role of storage, reduce the risk of full chamber and belt conveyor starting with load after the main engine stops. At the same time, the adjusting function of the silo can make the fine crushing chamber full of feeding, so that the aggregate shape of the finished product is better and the wear of the equipment is lower.

Better aggregates can reduce the amount of cement, increase workability, reduce the probability of blocking pipelines by pumping concrete, and reduce the cost of concrete mixing station. At the same time, they can also increase the strength of concrete, which is why high-grade concrete has strict control over the size of coarse aggregates.

In this process, the fine aggregate after medium crushing is screened out but not into fine crushing. The main reason is that the excessive content of fine aggregate fills the gap between coarse aggregates, reduces the crushing efficiency of fine crushing. At the same time, under the condition of full feeding, it is easy to cause the suffocation of fine crushing equipment and damage the equipment, reduce the service life of fine crushing equipment, and the pre-screening process measures can eliminate this hidden danger.

The third type of process:

The proportion of sand in commercial concrete aggregate is generally about 30%, and the amount of sand is relatively large. Under the current environment of exhaustion of natural sand resources and restriction of mining, machine-made sand has gradually become the trend and mainstream (at present, machine-made sand is mainly used in the construction of large-scale hydropower stations).

At present, machine-made sand mainly adopts vertical impact crusher. Because vertical impact crusher has the function of shaping and crushing, there are relatively many sand-making processes, such as vertical axis autocratic sand without producing coarse aggregates, and some sand-making processes give consideration to shaping coarse aggregates. This process takes into account both sand-making and shaping of 5-10mm aggregates (and all of them). Coarse aggregate is shaping.

The crushed aggregates and fine aggregates enter the screening workshop of the finished product 1, and the crude aggregates of the finished products of 10-20 mm and 20-31.5 mm are screened out. Some of the crude aggregates of the finished products of 10-20 mm and 20-31.5 mm and all the aggregates of 5-10 mm are put into the sand-making adjusting stockpile. After crushing and shaping by vertical shaft impact crusher, it enters the finished product 2 screening workshop for screening. All aggregates larger than 10mm are returned to the sand-making adjusting stockpile to form a closed-circuit cycle, and some more than 5-10mm are returned to the sand-making adjusting stockpile to form a closed-circuit cycle.

In order to adjust the fineness modulus of finished sand (medium sand is usually used to adjust the gradation of sand), some aggregates larger than 3-5 mm after screening are returned to the sand making workshop to form a closed-circuit cycle.

Luoyang Building Material and Architectural Design and Research Institute is a professional building material and building double-A design research institute. It has more than 20 years’ experience in mineral material research. According to the national policy requirements and the customers’ constant pursuit of new technology, it can provide a series of services, such as feasibility study report, design, general package, production improvement and intelligent transformation. Our Institute provides customization according to customers’needs. With the rapid development of gravel aggregate and the expansion of production scale, the design plan and process are based on the product quality, the product plan, equipment and construction site determined according to market conditions, and the environmental sanitation and safe operation are ensured.

Biomass energy is the only renewable energy source that can be stored. It can replace fossil energy to reduce CO₂. Therefore, it is a renewable energy with industrialization and large-scale utilization prospects. It is of great significance to the optimization of China’s energy structure. The development of biomass power generation is an important way to build a stable, economic, clean and safe energy supply system and break through the constraints of economic and social development resources and environment.

At present, three typical biomass power generation technologies in China are: biomass direct incineration power generation technology, biomass and coal mixed direct combustion power generation technology and biomass gasification power generation technology.

1. Biomass direct incineration power generation technology

Biomass direct incineration power generation is the direct combustion of biomass as a fuel for power generation or cogeneration.

Characteristics of biomass direct incineration power generation technology:
(1) The products of direct incineration of biomass are widely used, and ash can be comprehensively utilized;
(2) Direct biomass incineration can achieve large-scale reduction, harmless and resource utilization of various biomass resources at the fastest speed;
(3) After the direct combustion of biomass, the flue gas needs desulfurization and denitrification, and there is a risk that the atmospheric pollutants such as N0_X and SO₂ exceed the standard, and there is a risk of dioxin exceeding the standard.

2. Biomass and coal mixed direct combustion technology

Biomass and coal mixed direct combustion is the co-firing of biomass and biomass in pulverized coal furnace. It is a fast and low-cost biomass power generation technology that utilizes active power plants.It is also the cheapest and low-risk technology for generating electricity from renewable sources.

Characteristics of biomass and coal mixed direct combustion power generation:
(1) Pulverized coal combustion has high power generation efficiency, up to more than 35%. Biomass co-firing is the advantage of its high efficiency, which is unmatched by other biomass power generation technologies at this stage;
(2) Biomass burning low sulfur and low nitrogen, can reduce SO₂ and N0_X emissions from power plants when co-firing with coal powder;
(3) Since the straw-based biomass contains more inorganic substances such as K and Cl, it is easy to cause serious problems such as ash accumulation, slagging, agglomeration and corrosion of the heated surface during the combustion process, which is a serious challenge for biomass direct combustion technology.

3. Biomass gasification power generation technology
Biomass gasification is a technology in which biomass such as straw is heated in anoxic state, and carbon, hydrogen, oxygen and other elements are converted into a combustible gas of carbon monoxide, hydrogen, and methane, and converted into a gaseous fuel. The main combustible components of gasification gas are carbon monoxide, hydrogen, ethylene, methane, etc. It is a clean and clean green energy source.
Characteristics of biomass gasification power generation:
(1) Applicable to carbonization of various biomass raw materials;
(2) The calorific value of the gas is stable, and the generated gas calorific value is 1200-1300kcal/Nm³;
(3) The tar content in the gas is less than 30mg/Nm³, and the tar produced in the furnace passes the catalytic cracking conversion technology, and the tar content in the equipment is greatly reduced;
(4) High power generation efficiency;
(5) The ash after gasification is a good returning potash.

After years of in-depth research, Luoyang Building Material and Architectural Design and Research Institute has made the advantages of self-developed biomass gasification power generation technology more remarkable, and explored a new way for the resource utilization and treatment of agricultural production waste.

Luoyang Building Material and Architectural Design and Research Institute’s biomass gasification power generation technology innovation points:
(1) Modular design, compact structure, easy to install and transport;
(2) Continuous and stable production, which can achieve continuous operation for 300 days;
(3) The equipment adopts the material seal and mechanical seal double seal form, which is safe and reliable;
(4) The system adopts various temperature and pressure sensors and PLC intelligent operating system to realize automatic and efficient control;
(5) Gas washing and dust removal technology, dust removal treatment before hot steam condensation, to meet environmental protection requirements;
(6) The normal production of the system does not require external thermal energy to achieve self-sufficiency in energy;
(7) The normal production of the system can realize the comprehensive utilization of residual energy;
(8) Realize comprehensive energy supply, namely electricity, gas, fertilizer, cold and heat.

First、Process flow of sludge resource utilization

The sludge resource utilization means that the sludge undergoes a chemical reaction in a closed, anaerobic and high-temperature state, and the sludge is subjected to high-temperature pyrolysis and carbonization to produce combustible gas and bio-carbon.Thereby effectively decomposing the sludge, realizing the resource utilization, protecting the environment and achieving benefits.

1. Pressure filtration dehydration
By means of mechanical pressurization, the sludge is subjected to a pressure of 3-4Mpa to squeeze out free water between the sludge molecules. The high-efficiency filter press equipment can dehydrate 80% of municipal or industrial sludge to 50%. ;

2. Hydrothermal drying
The sludge water pyrolysis is to warm the sludge, so that a part of the cell material in the sludge is hydrolyzed, and the water in the cell is broken and separated, thereby facilitating the digestion of the subsequent sludge, and the water is hydrolyzed and dried to make the water 50% of the sludge is dried to 20% and can be sold directly as fuel;

3. Pyrolytic carbonization
Using advanced thermal machinery simulation technology and a large number of experimental analysis of sludge pyrolysis, Luoyang Building Materials Design and Research Institute developed the core unit of the process, sludge carbonization unit. The device can produce bio-carbon, activated carbon, building ceramsite, etc.; environmental protection can fully meet the requirements of Taihu Lake Basin and Beijing local environmental protection standards;

4. Calcination utilization
The bio-carbon and activated carbon produced by the carbonization process can be directly sold as products;

5. Production of building materials
Add some auxiliary materials and use brick making equipment to produce various building materials such as permeable floor tiles and wall tiles required for urban construction.

Second, the core technology of sludge resource utilization

Third, the innovation of sludge resource utilization

1. Water pyrolysis drying: using the latest low-energy water pyrolysis drying technology;
2. Multi-function: can realize different treatment requirements for sludge ceramsite + sludge carbonization + activation treatment;
3. Automation: computer control is used to realize unmanned field operation management;
4. High energy efficiency: high efficiency gas-solid heat exchange equipment with low heat consumption;
5. Reliable sealing: multiple sealing methods are adopted to ensure that the carbonization furnace is tightly sealed without leakage;
6. Emissions compliance: Clean and efficient exhaust gas treatment devices to meet the most stringent emission standards;
7. Adaptability: freely switch a variety of sludge without stopping the machine;
8. Wide adjustment range: the input amount can be changed by 0.5-3 times;
9. Low investment: equivalent to 15%-20% of the sludge-made ceramsite and sludge activated carbon production line.

In December 2018, Luoyang Building Material and Architectural Design  and Research Institute independently developed and designed, providing core equipment for sludge hydrolysis and carbonization resource utilization comprehensive utilization project, which was put into operation in Huzhou City, Taihu Lake, and treated 200 tons of sludge per day. The project is a demonstration project for the “13th Five-Year” National Sewage Special Treatment Sludge Resource Utilization, which has received extensive attention from governments at all levels and provided advanced solutions for environmental management in the Taihu Basin.

Summary of Soil Thermal Desorption Technology

Thermal desorption technology in soil remediation technology refers to the process that organic pollutants in soil are heated to a certain temperature by direct or indirect heat exchange under vacuum or when entering air, so that organic pollutants can be volatilized or separated from the polluted medium and enter the gas treatment system. Thermal desorption can selectively transform pollutants from one phase to another by adjusting heating temperature and residence time. There is no damage to organic pollutants in the process of remediation. By controlling the temperature of the thermal desorption system and the residence time of contaminated soil, the pollutants can be volatilized selectively without chemical reactions such as oxidation and decomposition. Thermal desorption mainly includes two basic processes: first, heating the substances to be treated, volatilizing the target pollutants into gaseous separation; second, condensing, collecting and incinerating the tail gas containing pollutants to discharge to the atmosphere after meeting the standards.

With the wide application of Engineering projects, thermal desorption has gradually developed into in-situ desorption (including hot gas, steam, etc.) and heterotropic thermal desorption (mobile thermal desorption equipment, rotary kiln thermal desorption equipment, microwave method, etc.).

Soil thermal desorption process
The heterotopic thermal desorption system can be divided into direct thermal desorption and indirect thermal desorption. It can also be divided into high temperature thermal desorption and low temperature thermal desorption.

(1) Direct thermal desorption consists of feed system, desorption system and tail gas treatment system. Feeding system: The contaminated soil is transported from workshop to desorption system through pre-treatment such as screening, dehydration, crushing and magnetic separation. Desorption system: After the contaminated soil enters the thermal rotary kiln, it contacts directly with the flame generated by the burner of the thermal rotary kiln, and is heated uniformly to the gasification temperature of the target pollutant, so as to achieve the purpose of separating pollutants from the soil. Tail gas treatment system: The tail gas enriched with gasification pollutants can remove the pollutants in the tail gas through cyclone dedusting, incineration, cooling, bag dedusting, alkali leaching and so on.

(2) Indirect thermal desorption consists of feed system, desorption system and tail gas treatment system. The difference from direct thermal desorption is the desorption system and the tail gas treatment system. Desorption system: The flame generated by burner uniformly heats the outside of rotary kiln. After heating to the boiling point of pollutants, pollutants are separated from soil and exhaust gas is discharged directly through combustion. Tail gas treatment system: The tail gas enriched with gasification pollutants can remove the pollutants in the tail gas through filters, condensers, ultrafiltration equipment and other links. Gas can be separated from oil and water by condensator to concentrate and recover organic pollutants.

The main equipments include feeding system, such as disperser, vibrating screen, chain conveyor, conveyor belt, iron remover, desorption system, rotary drying equipment or heat screw propulsion equipment, tail gas treatment system, cyclone dust remover, secondary combustion chamber, cooling tower, condenser, bag filter, washing tower, ultrafiltration equipment, etc.
Luoyang Building Material Architectural Design and Research Institute is a professional industrial kiln design unit, our soil remediation retort furnace processing capacity from 10 tons to 400 tons per hour, can be customized according to customer requirements modular product size.

Factors Affecting Soil Thermal Desorption

The treatment cycle of ectopic thermal desorption technology may be several weeks to several years. The actual cycle depends on the following factors:

(1) Volume of contaminated soil;
(2) Polluted soil and the nature of pollutants;
(3) Processing capacity of equipment. Generally, the capacity of a single processing equipment is between 3-200 tons/hour. The capacity of a direct thermal desorption equipment is larger, generally 20-160 tons/hour. The capacity of indirect thermal desorption is relatively small, generally 3-20 tons/hour.
The factors affecting the disposal cost of ectopic thermal desorption technology are as follows:
(1) Disposal scale;
(2) Water content of feed;
(3) Fuel type, soil properties, pollutant concentration, etc.

For small and medium-sized sites (less than 20,000 tons, about 26800 m3) abroad, the processing cost is about $100-300/m3, and for large sites (more than 20,000 tons, about 26800 m3), the processing cost is about $50/m3. According to the statistical data of domestic production and operation, the cost of thermal desorption and disposal of contaminated soil is about 600-2000 yuan/ton.

First, what is straw returning?

Straw returning is a kind of fertilization and fertilizer increase measure that is universally valued in the world today.
The air pollution caused by stalk incineration also has the effect of increasing fertilizer and increasing production. Straw returning can increase soil organic matter, improve soil structure, loosen soil, increase porosity, reduce capacity, and promote microbial vigor and crop root development.

Second, the harm of straw returning to the field?

According to a team of professors from the School of Environmental Sciences of Nanjing University, the research progress in the field of mercury biogeochemistry in rice fields found that, unlike the fixed effect on heavy metals, straw returning will greatly increase the accumulation of methylmercury in rice. Methylmercury is highly neurotoxic and can cause irreversible damage to the central nervous system and reproductive system of the human body. In recent years, studies have shown that rice is an important source of methylmercury exposure for inland residents. Therefore, an increase in the concentration of methylmercury in rice may lead to an increased risk of exposure to methylmercury in the population.

Third, how to solve the problem of straw returning to soil contaminated soil?

Faced with the increasingly serious situation of rural straw treatment and disposal, straw returning to the field will lead to the increase of soil pathogens, crop disease aggravation and lack of seedlings (frozen seedlings). Luoyang Building Materials Design and Research Institute takes advantage of industry technology. The straw gasification power generation technology is used to better solve the harm caused by straw returning and burning.

1. What is straw gasification power generation?
Straw gasification power generation is a technology in which biomass such as straw is heated in anoxic state to decompose and vaporize organic matter in the straw to produce a combustible gas. The combustible gas is used to drive the gas turbine to work to generate electricity.

2. Advantages of straw gasification power generation technology:
1) Wide adaptability of raw materials, adapt to various types of biomass straw, leaves and rhizomes;
2) The gas heat value is stable;
3) The tar content in the gas is less than 30mg/Nm3, and the tar produced in the furnace passes the catalytic cracking conversion technology, and the tar content in the equipment is greatly reduced;
4) High power generation efficiency;
5) The ash after gasification is a good return to the potash.

The straw gasification power generation technology of Luoyang Building Material and Architectural Design and Research Institute has changed the rural straw from disordered incineration to centralized treatment of power generation and fertilizer production, saving a lot of coal resources and increasing farmers’ income. Straw does not increase the amount of CO2 in the atmosphere during growth and combustion, and the sulfur content is extremely low, only 0.1%. The development of biomass power generation, replacing coal, can significantly reduce greenhouse gas emissions and has enormous environmental benefits.