Device for reducing content of hexavalent chromium in chromium oxide green

Abstract

The utility model discloses a device for reducing the content of hexavalent chromium in chromium oxide green. The device comprises a frame, a starting switch is arranged on the frame, a rotating roller and a first transmission part are arranged at the top of the frame, a feeding opening is formed in the top of the rotating roller, and a cover plate is arranged above the feeding opening; a reducing agent storage bin and a chromium oxide green storage bin are arranged above the rotating roller, a first metering screw is arranged at the bottom of the reducing agent storage bin, a second metering screw is arranged at the bottom of the chromium oxide green storage bin, and discharging ports of the first metering screw and the second metering screw are aligned to a feeding port in the top of the rotating roller; the bottoms of the first metering screw and the second metering screw are connected with the top of the frame through connecting rods. Chromium oxide green and a reducing agent are added into the chromium oxide green storage bin and the reducing agent storage bin respectively, then the first metering screw and the second metering screw are controlled to feed materials in proportion, and after the set reaction time is reached, the materials flow out from a feeding port of the rotating roller rotating continuously and are scraped out through the discharging scraper.

Description

Technical Field

[0001] This utility model relates to the field of chromium salt production equipment, specifically to a device for reducing the hexavalent chromium content in chromium oxide green. Background Technology

[0002] Chromium oxide green, also known as chromium trioxide (Cr2O3), is a green powder with a metallic luster and magnetism, used in the smelting of metallic chromium and chromium carbide. However, chromium oxide green usually contains hexavalent chromium, and the presence of hexavalent chromium can cause the following problems: (1) Hexavalent chromium not only increases the content of water-soluble substances, but also makes the product yellow, affecting its use; (2) Hexavalent chromium compounds are highly toxic chemicals that can enter the human body through the digestive tract, respiratory tract, skin and mucous membranes. Long-term or short-term exposure or inhalation may cause cancer and affect human health; (3) Hexavalent chromium can persist in the environment and has a high bioaccumulation capacity and danger; (4) Hexavalent chromium compounds may also cause hereditary gene defects, which can have a serious impact on the ecosystem. Therefore, the Ministry of Ecology and Environment, together with the National Health Commission, has included hexavalent chromium compounds in the "List of Toxic and Hazardous Water Pollutants" and has strictly supervised and controlled them in order to improve the quality of the water environment, prevent and control water environment risks, reduce the adverse effects of toxic and harmful substances on the water environment and human health, and protect public health and environmental safety.

[0003] Currently, methods to reduce the hexavalent chromium content in chromium oxide green involve either calcining chromic anhydride with a small amount of boric acid, or calcining chromium oxide green containing hexavalent chromium with a small amount of boric acid, then simultaneously cooling the chromium oxide green obtained from the thermal decomposition of chromic anhydride in a sealed container pre-filled with urea. After washing to remove water-soluble substances, the chromium oxide green is suspended in a urea solution and finally heat-treated at 200-280℃. The chromium oxide green obtained from the thermal decomposition of chromic anhydride is then pulverized with a small amount of ethanol in a vibratory mill to obtain the chromium oxide green product. While this method can reduce the hexavalent chromium content in chromium oxide green, it suffers from problems such as complex operation, large additive dosage, and high production costs. Another method to reduce the hexavalent chromium content in chromium oxide green is the pulping and washing process, which mainly includes steps such as room temperature pulping, reduction, washing, filtration, and drying. This process is complicated, has high operating costs, and requires large equipment investments. Furthermore, when removing hexavalent chromium from chromium oxide green through pulping and washing at room temperature, trace amounts of hexavalent chromium cannot be completely washed out, resulting in the chromium oxide green product still containing hexavalent chromium, which affects product performance. In addition, a certain amount of chromium oxide green is lost during the chromium removal process, further increasing production costs. Utility Model Content

[0004] This invention provides a device for reducing the hexavalent chromium content in chromium oxide green. The purpose is to remove hexavalent chromium from chromium oxide green using a simple processing technology, thereby reducing production costs, improving the performance of chromium oxide green products, and reducing the environmental pollution caused by hexavalent chromium.

[0005] To achieve its purpose, this utility model adopts the following technical solution:

[0006] A device for reducing the hexavalent chromium content in chromium oxide green includes a frame with a start switch and a rotating drum driven by a drive shaft at the top of the frame. A first transmission unit is located at the top of the frame, and its output end is connected to the drive shaft. A feeding port is located at the top of the rotating drum, and a cover plate is located above the feeding port. The cover plate is opened and closed by a tilting cylinder located at the top of the rotating drum, controlled by a time relay. Above the rotating drum are a reducing agent storage silo and a chromium oxide green storage silo. At the bottom of the reducing agent storage silo is a first metering screw driven by a second transmission unit, and at the bottom of the chromium oxide green storage silo is a second metering screw driven by a third transmission unit. The discharge ports of both the first and second metering screws are aligned with the feeding port at the top of the rotating drum. The bottoms of the first and second metering screws are connected to the top of the frame via connecting rods. Below the rotating drum is a discharge scraper driven by a fourth transmission unit.

[0007] The start switch and time relay are electrically connected to the signal input terminals of the PLC programmable controller, and the signal output terminals of the PLC programmable controller are electrically connected to the tilting cylinder, the first transmission unit, the second transmission unit, the third transmission unit, and the fourth transmission unit.

[0008] Furthermore, the drive shaft of the hexavalent chromium removal device is supported at both ends by bearing housings.

[0009] Furthermore, the rotating drum is supported by the first bracket, and the first transmission unit is supported by the second bracket.

[0010] Furthermore, in the hexavalent chromium removal device, the fixed end of the tilting cylinder is connected to the rotating drum, and the movable end of the tilting cylinder is connected to the cover plate via pins.

[0011] Furthermore, the output end of the first transmission unit is connected to the transmission shaft via a coupling.

[0012] Furthermore, both the reducing agent storage silo and the chromium oxide green storage silo are conical in shape.

[0013] Furthermore, both the frame and the connecting rods are hollow structures.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0015] When removing hexavalent chromium from chromium oxide green using the device of this invention, chromium oxide green and a reducing agent are simply added to the chromium oxide green storage silo and the reducing agent storage silo, respectively. Then, a PLC programmable controller controls the rotation of the second and third transmission units, thereby controlling the first and second metering screws to feed the materials proportionally. After all the chromium oxide green and reducing agent have entered the rotating drum, the PLC programmable controller controls the rotation of the first transmission unit to drive the rotating drum to perform the reduction reaction. After the set reaction time is reached, a time relay transmits a signal to the PLC programmable controller. The PLC programmable controller receives the signal and controls the tilting cylinder to open the cover plate, allowing the material to flow out from the continuously rotating drum's feeding port and finally be scraped out by the discharge scraper. The entire device can automatically complete the feeding and discharging process, exhibiting a high degree of intelligence, simple process, stable operation, low operating cost, and strong practicality. By adding a reducing agent to chromium oxide green and then carrying out a reduction reaction in the rotating drum, the hexavalent chromium in the chromium oxide green is reduced to trivalent chromium, thereby reducing the hexavalent chromium content in the chromium oxide green and improving the recovery rate of metallic chromium. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the device for reducing the hexavalent chromium content in chromium oxide green according to this utility model;

[0017] Figure 2 This is a schematic diagram of the discharge scraper conveyor of this utility model;

[0018] In the diagram: 1-Frame; 2-Rotating drum; 3-Tilting cylinder; 4-Cover plate; 5-First metering screw; 6-Reducing agent storage silo; 7-Chromium oxide green storage silo; 8-Second metering screw; 9-First transmission unit; 10-Bearing seat; 11-Discharge scraper conveyor; 12-Feeding port; 13-First support; 14-Second support; 15-Drive shaft; 16-Second transmission unit; 17-Third transmission unit; 18-Connecting rod; 19-Fourth transmission unit. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings:

[0020] This invention relates to a device for reducing the hexavalent chromium content in chromium oxide green. It includes a hollow frame 1 with a start switch. A rotating drum 2, driven by a drive shaft 15, is connected to the top of the frame 1 via a first bracket 13. A feeding port 12 is located at the top of the rotating drum 2, and a cover plate 4 is positioned above the feeding port 12. The cover plate 4 is opened and closed by a tilting cylinder 3 located at the top of the rotating drum 2. The tilting cylinder 3 is controlled by a time relay. The fixed end of the tilting cylinder 3 is connected to the rotating drum 2, and the movable end of the tilting cylinder 3 is connected to the cover plate 4 via pins. The first bracket 13 is located on one side of the top of the frame 1, and a second bracket 14 is located on the other side, with the first bracket 13 and the second bracket 14 arranged coaxially. A first transmission unit 9 is connected to the top of the frame 1 via the second bracket 14. The output end of the first transmission unit 9 is connected to the drive shaft 15 via a coupling, and both ends of the drive shaft 15 are supported by bearing seats 10. Above the rotating drum 2 are a cone-shaped reducing agent storage hopper 6 and a chromium oxide green storage hopper 7. The bottom of the reducing agent storage hopper 6 is equipped with a first metering screw 5 driven by a second transmission unit 16, and the bottom of the chromium oxide green storage hopper 7 is equipped with a second metering screw 8 driven by a third transmission unit 17. The discharge ports of the first metering screw 5 and the second metering screw 8 are aligned with the feeding port 12 at the top of the rotating drum 2. The bottoms of the first metering screw 5 and the second metering screw 8 are respectively connected to the top of the frame 1 through a hollow connecting rod 18. Below the rotating drum 2 is a discharge scraper 11 driven by a fourth transmission unit 19.

[0021] The start switch and time relay are electrically connected to the signal input terminals of the PLC programmable controller, and the signal output terminals of the PLC programmable controller are electrically connected to the tilting cylinder, the first transmission unit, the second transmission unit, the third transmission unit, and the fourth transmission unit.

[0022] To remove hexavalent chromium from chromium oxide green, simply add chromium oxide green and reducing agent to the chromium oxide green storage silo 7 and the reducing agent storage silo 6, respectively. Then, the PLC programmable controller can control the rotation of the second transmission unit 16 and the third transmission unit 17, thereby controlling the first metering screw 5 and the second metering screw 8 to add materials proportionally. After all the chromium oxide green and reducing agent have entered the rotating drum 2, the PLC programmable controller controls the rotation of the first transmission unit 9 to drive the rotating drum 2 to rotate for the reduction reaction. After the set reaction time is reached, the time relay transmits a signal to the PLC programmable controller. The PLC programmable controller receives the signal and controls the tilting cylinder 3 to run, thereby opening the cover plate 4. The material flows out from the feeding port of the continuously rotating drum 2 and is finally scraped out by the discharge scraper 11.

Claims

1. An apparatus for reducing the hexavalent chromium content in chromium oxide green, characterized in that: The frame (1) includes a frame (1) with a start switch. A rotating drum (2) driven by a drive shaft (15) is located at one top end of the frame (1). A first transmission part (9) is located at the other top end of the frame (1), and the output end of the first transmission part (9) is connected to the drive shaft (15). A feeding port (12) is located at the top of the rotating drum (2). A cover plate (4) is provided above the feeding port (12). The cover plate (4) is opened and closed by a flipping cylinder (3) located on the top of the rotating drum (2). The flipping cylinder (3) is controlled by a time relay. A reducing agent storage silo (6) and a chromium oxide green storage silo (7) are provided above the rotating drum (2). A first metering screw (5) driven by a second transmission unit (16) is provided at the bottom of the reducing agent storage silo (6). A second metering screw (8) driven by a third transmission unit (17) is provided at the bottom of the chromium oxide green storage silo (7). The discharge ports of the first metering screw (5) and the second metering screw (8) are aligned with the feeding port (12) at the top of the rotating drum (2). The bottoms of the first metering screw (5) and the second metering screw (8) are connected to the top of the frame (1) by a connecting rod (18). A discharge scraper (11) driven by a fourth transmission unit (19) is provided below the rotating drum (2). The start switch and time relay are electrically connected to the signal input terminal of the PLC programmable controller, and the signal output terminal of the PLC programmable controller is electrically connected to the tilting cylinder (3), the first transmission unit (9), the second transmission unit (16), the third transmission unit (17) and the fourth transmission unit (19).

2. The apparatus for reducing the hexavalent chromium content in chromium oxide green as described in claim 1, characterized in that: The drive shaft (15) is supported at both ends by bearing seats (10).

3. The apparatus for reducing the hexavalent chromium content in chromium oxide green as described in claim 2, characterized in that: The rotating drum (2) is supported by the first bracket (13), and the first transmission part (9) is supported by the second bracket (14).

4. The apparatus for reducing the hexavalent chromium content in chromium oxide green as described in claim 3, characterized in that: The fixed end of the flipping cylinder (3) is connected to the rotating drum (2), and the movable end of the flipping cylinder (3) is connected to the cover plate (4) by pins.

5. The apparatus for reducing the hexavalent chromium content in chromium oxide green as described in claim 4, characterized in that: The output end of the first transmission unit (9) is connected to the transmission shaft (15) via a coupling.

6. The apparatus for reducing the hexavalent chromium content in chromium oxide green as described in claim 5, characterized in that: Both the reducing agent storage silo (6) and the chromium oxide green storage silo (7) are conical.

7. The apparatus for reducing the hexavalent chromium content in chromium oxide green as described in any one of claims 1-6, characterized in that: Both the frame (1) and the connecting rod (18) are hollow structures.

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