3.Characteristics of oily wastewater and its treatment methods

Oily wastewater mainly comes from petroleum, petrochemical, iron and steel, coking, gas generating station, machining and other industrial sectors. Except for the relative density of heavy tar above 1.1, the relative density of oil pollutants in wastewater is less than 1. Oil usually exists in three states in wastewater. (1) Oil slick, oil droplet size greater than 100 um, easy to separate from wastewater ;(2) dispersed oil, oil droplet size between 10~100 um, suspended in water ;(3) emulsified oil, oil droplet size less than 10 um, not easy to separate from wastewater. Waste due to different industrial sectors  The concentration of oil in water varies greatly, such as wastewater produced in refining process, oil content is 150~1000 mg\L, tar content in coking wastewater is about 500~800. Therefore, the treatment of oily wastewater should first use cadmium oil tank, recovery oil slick or heavy oil, treatment efficiency is 60~80, oil content in effluent is about 100~200 mg\L; emulsified oil and dispersed oil in wastewater are difficult to treat, Therefore, to prevent or reduce the phenomenon of emulsification. One of the methods is to reduce waste during production  The emulsification of oil in water; second, in the treatment process, as far as possible to reduce the number of pumps to lift the wastewater, so as not to increase the degree of emulsification. The treatment methods are usually air floatation and demulsification.

4.Characteristics of cyanide-containing wastewater and its treatment methods

Cyanide wastewater mainly comes from electroplating, gas, coking, metallurgy, metal processing, chemical fiber, plastics, pesticides, chemical industry and other departments. Cyanide wastewater is a kind of industrial wastewater with great toxicity, which is unstable in water and easy to decompose. Inorganic cyanide and organic cyanide are local toxic substances, and human ingestion can cause acute poisoning. The lethal dose of cyanide to human body is 0.18 g, potassium cyanide is 0.12 g, the mass concentration of cyanide to fish is 0.04~0.1 mg\L. in water The main treatment measures of cyanide-containing wastewater are as follows :(1) reforming the process to reduce or eliminate the effluents of cyanide-containing wastewater, such as using cyanide-free electroplating method to eliminate electroplating Workshop industrial wastewater. (2) Wastewater with high cyanide content should be recycled, and wastewater with low cyanide content should be purified and treated before discharge. The recovery methods include acidified aeration and lye absorption, steam desorption and so on. The treatment methods include alkaline chlorination, electrooxidation, pressurized hydrolysis, biochemistry, biological iron, ferrous sulfate, air blowing hair loss and so on. The alkaline chlorination method is widely used, the ferrous sulfate method is not thorough and stable, and the air blowing method not only pollutes the atmosphere, but also fails to meet the discharge standard.

A good design scheme can not be separated from the understanding of water quality; understanding the source and characteristics of wastewater and the production process is of great help to our design scheme and selection of treatment process. We plan to collect all kinds of industrial wastewater sources, characteristics and treatment methods, hope to be used for reference and sharing industrial water treatment industry colleagues, learn from each other, together for the development of water treatment industry in China.
Industrial wastewater refers to the wastewater discharged from the industrial production process, including process water, cooling water for machinery and equipment, flue gas washing water, equipment and site washing water, etc. Because of the variety of industrial types, each industry is composed of multi-stage processes, the properties of wastewater are completely different and the composition is very complex. According to the different harm caused by wastewater to environmental pollution, it can be roughly divided into solid pollutants, organic pollutants, oil pollutants, toxic pollutants, biological pollutants, acid and alkali pollutants, aerobic pollutants, nutritional pollutants, sensory pollutants and thermal pollution.

1. Characteristics and Treatment of Acid-base Wastewater

Acid wastewater mainly comes from iron and steel plants, chemical plants, dye plants, electroplating plants and mines, which contain various harmful substances or heavy metal salts. The mass fraction of acid varies greatly, the low is less than 1 and the high is more than 10. Alkaline wastewater mainly comes from printing and dyeing factory, leather factory, paper mill, refinery and so on. Some of them contain organic bases or inorganic bases. Some of the mass fractions of alkali are higher than 5 and some are lower than 1. Acid and alkali wastewater, in addition to containing acid and alkali, often contains acid salt. Basic salts and other inorganic and organic compounds.

 Acid and alkali wastewater has a strong corrosion, need to be properly treated before discharge.
 The principle of treating acid-base wastewater is:
 (1) High-concentration acid-base wastewater should be recycled as a matter of priority. According to the requirements of water quality, quantity of water and different processes, plant or regional scheduling should be carried out for reuse as far as possible; if reuse is difficult, or if the concentration is low and the quantity of water is large, acid-base can be recovered by concentrated method.
 (2) Low-concentration acid-base wastewater, such as cleaning water from pickling tanks and rinsing water from alkali washing tanks, shall be neutralized.

For neutralization treatment, the principle of waste treatment should be considered first. For example, acid and alkali wastewater neutralize each other or use waste alkali (slag) to neutralize acid wastewater, and use waste acid to neutralize alkaline wastewater. In the absence of these conditions, neutralizers can be used.

According to the requirements of the new rural construction and the strengthening of people’s awareness of environmental protection and energy conservation, now, pig farms build biogas digesters and biochemical ponds to treat feces and urine, but the fecal materials into biogas digesters have not been separated from solid and liquid. The actual use proves that the direct biogas culture effect is not ideal. Because untreated fecal water enters the biogas digester, the organic load per unit volume of the biogas digester is greatly increased, so the volume of the biogas digester is much increased.

Because of the long-term use of biogas digester, a large amount of residue is left behind after fermentation, which makes the biogas digester blocked and the capacity decreases, which results in the biogas digester can not be used, and the cleaning pool is extremely inefficient and unsafe, and the cost is increased at the same time. If the direct sale of fresh pig manure is difficult to transport. Therefore, we find that solid-liquid separation measures should be carried out before pig manure, which can not only solve the problem of pig manure precipitation in biogas digesters, greatly enhance the treatment capacity of biogas digesters, but also greatly reduce the construction area of biogas digesters and biochemical ponds.

Save the construction investment and land use area of environmental protection treatment, the separated pig manure can also be directly used as fruit trees, tree fertilization and organic fertilizer raw materials. Sell to organic fertilizer plant as organic fertilizer raw material or self-made organic fertilizer, both social and economic benefits. This machine can be widely used as chicken, cattle, horse and all kinds of intensive farms for the separation of animal feces, distiller’s grains, residue, starch residue, sauce residue, slaughtering plant and other high concentration organic sewage residue.

The practicability of flat centrifuge: the separation speed of slag liquid is fast, the moisture content of fecal slag after separation is between 50-60%, the amount of slag and water content can be adjusted, it can be used for different ingredients of feed (such as grass and concentrate feed), easy to transport, Its solid particles are suitable for fish feed and organic fertilizer raw materials.

Advanced: flat centrifuge decontamination ability, no blockage, easy to clean. The solid content, chemical oxygen consumption, total oxygen consumption, nitrogen and phosphorus removal rate of treated fecal and urine water can be between 70 and 95% respectively.

Durability: the frame, sieve frame, screen and so on of plate centrifuge are made of stainless steel and anticorrosion treatment, etc., corrosion resistance, high strength, long service life.

Economy: flat centrifuge automation, low power consumption, low price. Easy to operate simply press the start stop button

Before the introduction of decanter centrifuge into the field of tailings recovery, the traditional way is to discharge a large amount of unqualified tailings. With the deepening of the concept of environmental protection, the mineral processing industry can not find a balance between water pollution control and production, which seriously restricts the healthy development of tailings washing industry. The following three advantages of decanter centrifuge in tailings washing field are discussed to discuss the adaptability value of centrifuge to industry.

Separation and recycling of tailings solid-liquid by decanter centrifuge:

The decanter centrifuge is introduced into the field of washing washing and pollution control. The sewage pretreatment is added with precipitator flocculant and then entered into the purification tank. First, the concentrate powder in the tailings washing wastewater is separated by the horizontal screw centrifugal solid liquid, which increases the utilization efficiency of resources and reduces the waste of resources.

Regeneration and utilization of mineral processing wastewater by decanter centrifuge:

The pretreatment water quality of tailings washing wastewater by decanter centrifuge can participate in production again, and participate in production recycling again to save cost or discharge. The recycling of water resources reduces the consumption of water resources in the industry, not only reduces the cost, but also saves energy and is more environmentally friendly;

Adding added value to tailings particle classification by decanter centrifuge:

Recovery of concentrate powder, in the decanter centrifuge solid-liquid separation stage can be selected and graded ore powder particle size, purification and classification of concentrate powder quality, increased the value-added deduction cost to create value;

GN decanter centrifuge separation precision high processing capacity is small, the use of decanter centrifuge to treat wastewater to the original sedimentation tank transport pipeline compatibility, no major changes to reduce the cost of capital construction, Because of the advantages of simple operation, low processing cost and reliable operation, solid-liquid separation has been widely used in sewage treatment industry.

The above is about the case of decanter centrifuge turning waste into treasure into profit in the separation of solid liquid from tailings of concentrator. Through the input-output ratio of decanter centrifuge to demonstrate the value of creating wealth of centrifuge equipment, Wealth is around only in the pitch between hope to inspire you!

GN has a range of tailing washing decanter centrifuges for you choice. Please contact us for more information.

The spiral sedimentation centrifuge has reasonable structure, advanced technology and fine manufacture. It can concentrate, dehydrate or separate solid particles in the range of several microns to three millimeters.
Product characteristics :

1, Good adaptability: in the process of fully considering the material, the process of various special requirements for centrifuges, the primary components of the implementation of special, adjustable optimization design. As long as the user before the purchase of the installation and use of the place, material processing physical and chemical characteristics, process requirements and so on, we will provide users with the most suitable model. High degree of

• Automation: centrifuge in the work of feeding, separation, unloading, and other processes are carried out in high speed continuous automatic operation. The automatic control of centrifugal separation and centrifugal scour process is completed by programmable controller.
• Stability The differential used in centrifuge is cycloid wheel differential or planetary wheel differential, which has the characteristics of large torque and wide conditioning range.
• Performance is strong: the centrifuge adopts the double motor double frequency conversion energy reaction differential speed system to control, carries on the flexible stepless conditioning to the differential speed, and adjusts the differential speed at any time according to the material change. real energy saving products. Good
• Operation environment: centrifuge separation of materials is carried out under completely closed conditions, to ensure that the operation site is neat, and to maintain the production environment neat and hygienic, to complete civilized production.
• Safety maintenance device is completely reliable: centrifuge with torque maintenance, power control and other multiple maintenance can effectively eliminate or reduce the damage caused by sudden failure to the machine. Beautiful 7. Shape: the machine seat is welded by carbon steel, the appearance is treated by special technology, lubrication is smooth.

The horizontal screw centrifuge is a equipment for separating suspension by centrifugal sedimentation principle. Its working principle is that when the separated suspension enters the drum of the centrifuge, the solid particles with higher density than the liquid phase quickly settle to the inner wall of the drum under the centrifugal force of the drum. The separated liquid flows out from the overflow Weir of the drum. This horizontal screw centrifuge can feed, separate, wash and unload continuously at full speed. Compact structure, continuous operation, smooth operation, strong adaptability, production Large capacity, convenient maintenance and other characteristics. suitable for separating suspensions with solid-containing particle size greater than 0.005 mm, concentration range of 2-40%. Widely used in chemical, light industry, pharmaceutical, food, environmental protection and other industries.

Screw conveyor is through rotating blade, push the material, widely used in building materials, chemical, electric power, metallurgy, coal mine, grain and other industries. Screw conveyor is suitable for horizontal or inclined conveying powder, granular and small block materials, the temperature of general materials should be less than 200℃, it is not suitable for conveying materials that are prone to deterioration, easy to caking or sticky. Today, we introduce the advantages and disadvantages of screw conveyor, which is convenient for customers to understand and use.

 I. Advantages of screw conveyors

 (1) Spiral shaft and shaft are connected by embedded tongue type, which makes installation, disassembly and maintenance very convenient and has less failure rate.

 (2) The screw conveyor adopts variable diameter structure, and the lifting bearing can not contact with the material, so its life is long.

 (3) It is not easy to jam or block the material when conveying, and the head and tail bearing seat is outside the shell, the seal of the bearing is good can be used for a long time.

(4) The structure is simple and the size is small, so the occupied area and space are not very large.

(5) There may be multiple feed and discharge ports, which can be arranged flexibly.

 (6) It is delivered in a reversible direction and therefore can be delivered in both directions.

 (7) Safe and reliable operation, can complete transportation, mixing, stirring, loose, heating and cooling processes.

 II. Disadvantages of screw conveyors

 (1) The friction between the blade, the casing and the material is relatively large, which makes the blade and the casing easy to wear, and the power consumption is also relatively large.

 (2) The transport distance is limited and can not exceed the maximum requirement.

 III. Selection of screw conveyor diameters

 For the screw diameter of the winch conveyor, the requirements should be met:

 In the case of conveying bulk material, the screw diameter shall be 10 times the maximum side length of the particle;

 If there are only a small number of large particles, the spiral diameter should be 4 times the maximum side length of the particle.

GN can customize screw conveyors upon customers’ request. No matter O-type or U-type, GN is able to fabricate quality products specially for clients’ needs and requirements. We have standard products for multiple usage. Please contact us if you are interested in this product.

How much is the maximum tilt angle of the screw conveyor, depending on what specifications the screw conveyor is, the screw conveyor is divided (tube type, U type, no shaft, have shaft), and then what material is transported is related to this screw conveyor angle problem.

When the screw conveyor is used to transport the material horizontally, the material is pushed by the screw blade. When the internal friction force between the material layers is greater than the external friction force between the material and the groove wall, the material flow is stable when the ratio of the height of the material layer to the width of the machine slot is satisfied. The the material is transported vertically, it depends on the property of the material. The material in the machine slot is pushed by the spiral piece in the direction of movement. The lower part is continuously fed to prevent the upper material from sliding, resulting in lateral side pressure, thus increasing the internal friction of the material. on transportation to form a continuous material flow. Because the spiral vibrates in the movement, the material arch will be destroyed and formed sometimes, which makes the material lag for the spiral gap in the transportation process, which affects the conveying capacity.

What is the maximum tilt angle of the screw conveyor? For the same material, there are shaft, no shaft, tube, U type, etc., the same speed ratio of screw conveyor is the same type, their conveyor quantity is different, not to mention if there is tilt angle, the conveying quantity is more different, because screw conveyor has tilt angle, material has backflow phenomenon, so the conveyor quantity is different.
For the same type of speed ratio screw conveyor, under the condition of conveying the same material and angle, the axial tube type screw conveyor is larger, and the U type screw conveyor without shaft is smaller. the maximum tilt angle of shaft tube screw conveyor is 45°, and the maximum tilt angle of shaft tube screw conveyor is 30°. The maximum tilt angle of U screw conveyor with and without shaft is °20-30.

Remark: The greater the angle of the screw conveyor, the same speed ratio and model screw conveyor, the transport volume will be weakened. Screw conveyor is often used for dust removal equipment.

Centrifuge is a machine that uses centrifugal force to separate the components of a liquid from a solid particle or a mixture of liquid and liquid. Mainly used in chemical, petroleum, food, pharmaceutical and other industries. There are many kinds of centrifuges, let’s talk about the operation process and advantages of industrial centrifuges.

The characteristic of industrial centrifuge is that it can automatically carry on the cycle operation of feeding, separating, washing, drying, discharging, washing net and so on. The operating time of each process can be automatically controlled by the electrical hydraulic system according to the procedure according to the predetermined requirements, or it can be operated directly by manual.

When the industrial centrifuge is operated, the feed valve opens automatically, the suspension enters the drum running at full speed, the liquid phase is thrown out of the drum through the filter net and the small hole in the drum wall, and then flows out through the outlet of the casing. The slag left in the drum is evenly distributed on the filter surface by rake teeth. When the filter slag reaches the specified thickness, the feed valve automatically closes. Then the flushing valve is opened automatically, and the washing liquid is sprayed on the filter slag for a certain time, and the valve is automatically closed. After drying for a certain time, the scraper rises automatically, the filter slag is scraped and discharged through the inclined chute. When the scraper rises to the limit position, it automatically recedes, and the flushing valve is opened to flush the filter. For a certain duration After time, complete an operation cycle. re-start feed into the next operation cycle.

Industrial centrifuges have the advantages of strong adaptability to materials, the particle size of solid particles can be used from very fine to very coarse; the concentration of suspension and the change of feed is not sensitive; filter, washing time can be freely adjusted; filter slag dry, and can get very good washing; generally at full speed to complete each process, production capacity; can filter or settle some difficult to separate suspensions.

GN produces quality centrifuges that can be applied in many industries and fields, such as mining, chemical, petroleum, food and beverage, edible oil, pharmaceutical etc. Please contact us for more information.

1. Working Principle of Vertical Vibration Discharge Centrifuge

In general, the vertical and horizontal centrifuge structure is not different, the difference is mainly arranged in different ways, vertical is vertical. The working principle of vertical centrifuge is that the staff put the material into the machine through the funnel, pay attention to the distribution must be evenly when placed. When the machine is running, the material can be thrown into the cone of the sieve basket by centrifugal force at high speed. Among them, because its vibration is axial, its material also moves from top to bottom with the whole sieve surface, and then realizes the separation of solid and liquid. The separated liquid can be discharged through the sink. In addition, the vibration of the machine can keep the material loose  state, so that the overall dehydration effect is more obvious.

2. Working principle of Horizontal vibrating discharge centrifuge

In horizontal high-speed vibration dynamic discharge axial centrifuge, the material is mainly subjected to two axial centrifugal forces. One main force is the axial centrifugal force which rotates at high speed along the rotating direction of the inertia diameter of the vibrating animal material; the other is the centrifugal force which comes from the direction of the inertia axis of the vibrating material along the rotation direction of the material diameter. because the internal \915; centrifugal gravity of the material and the factor of its separation rate are usually much smaller compared with the centrifugal force factor of the material axis upward, the axial centrifugal force factor is negligible.

The direction and numerical value of the two vibrating inertial friction forces on the internal movement of the various materials to be processed can always change. The centrifugal force can C be divided into two forces, that is, Cp and Ct,. The inertial force of vibration can also be decomposed into JP and Jt.. If the result is greater than the friction between the input material and the sieve surface, the material will move outward, that is, the discharge.

3. Working principle of scraper discharge centrifuge

In general, scraper discharge centrifugal opportunities according to the distribution of sieve basket in which the distinction is horizontal and vertical. The operation principle of the machine is mainly through centrifugal force to achieve filtration, when the wet coal enters, it will reach between the sieve basket and the scraper of the screw, and then through centrifugal force, the centrifugal liquid is discharged through the whole material from the screen and into the sink, and finally out of the machine, the material that drains the water will remain inside the screen. But there is a certain speed difference between the sieve basket and the screw scraper, which makes the scraper can scrape out the coal particles and finally get the dry coal.

The spiral corner spacing on the scraper shaft refers to the angle between the trajectory of the centrifuge coal flow motion and the centrifuge sieve strip. at present, assuming that the measured value β=45~60°, the effective width of the sieve seam is determined to be Bβ=b/sinβ(where, b/snβ is the scraper pitch of the centrifuge). It can be seen that the correct selection of appropriate scraper pitch is very important for the dehydration of centrifuges [2]. moreover, the gap between the scraper and the sieve basket is required to be (2±1) mm, this gap can be adjusted by increasing or decreasing the mat on the flange of the shaft or decrease the scraper.

Decanter centrifuge is a continuous operation of settling equipment. Choosing a suitable decanter centrifuge can not only solve the production problem and improve the working efficiency, but also save the production cost and reduce the operating risk. The following is to introduce the main points of maintenance and maintenance of decanter centrifuge.

1. for bag type coarse effect or medium effect filter, under normal use condition, general use 7-9 weeks should replace new.

2. for sub-efficient filters, under normal operating conditions, the general use of 5-6 months, should also be replaced.

3. all kinds of filters before the device, do not promise to open the bag or packaging film; and according to the packing box marked on the biased storage filter; in the handling process, should be light, light release, to prevent violent vibration and collision.

4. for high-efficiency filters, the device bias must be accurate: when using corrugated plate combination filter in vertical device, corrugated plate must be perpendicular to the ground; filter in vertical and frame connection, strictly prohibited leakage, deformation, breakage and leakage of glue, etc., after the device must be wrapped inside clean, free of dust, oil, rust and debris.

5. the high efficiency filter is installed, the arrow on the outer frame should be consistent with the airflow direction; when it is installed vertically, the filter paper crease direction should be perpendicular to the ground.

6. transport and storage of efficient filters shall be shelved in accordance with the direction of the factory signs. Lying screw centrifuge in the transport process, should be light to take light release, to prevent violent vibration and collision, do not allow rough loading and unloading.

7. the high efficiency filter must be unpacked at the installation site before installation for appearance inspection, including: filter paper, sealant and frame damage; side length, diagonal and thickness dimensions meet the requirements; frame with or without burrs and rust spots; with or without product certification, technical performance meets the design requirements. Then according to the standard “clean room construction and acceptance code” the method of inspection, qualified should be installed immediately.

8. the cleanliness level is equal to and higher than the high efficiency filter used in the clean room of class 100, the detected according to the method specified in the clean room construction and acceptance code before installation, and the required requirements shall be met.

To be continued