An improved rotary kiln for efficient reduction of iron-containing waste slag

Abstract

This utility model discloses an improved rotary kiln for efficient reduction of iron-containing waste slag. It includes a feed hopper (1), a feed screw conveyor (2), a flue hood (3), a kiln body (4), a kiln body support roller device (5), a kiln body transmission device (6), a kiln body baffle roller device (7), a discharge end sealing cover (8), a kiln inner wall insulation layer (9), a heating spray gun (10), and a discharge screw conveyor (11). Based on the characteristics of the roasting raw materials and the process characteristics of high-temperature reduction roasting, the feed and discharge ends of a conventional rotary kiln are modified to be airtight. During roasting, a sealed space is formed inside the kiln. The kiln body insulation layer is constructed with a spiral-shaped refractory brick layer to increase the reducing concentration inside the kiln and the dispersion of materials during movement, achieving efficient reduction. After the application of this improved rotary kiln, low-cost, high-efficiency reduction roasting is achieved.

Description

Technical Field

[0001] This utility model belongs to the field of non-ferrous metal smelting technology, specifically relating to an improved rotary kiln for high-temperature reduction roasting of iron-containing waste slag in a sealed kiln body. Background Technology

[0002] In the field of non-ferrous metal smelting, the efficient resource utilization of iron-containing waste slag has always been a key focus of industry technological research. This type of waste slag is mainly composed of nickel, copper, lead, and zinc smelting slag, with typical components including 15%-46% TFe and valuable metals such as nickel, copper, and cobalt, while also containing complex silicate mineral structures. Currently, there are four treatment methods for this type of iron slag. The first is direct smelting and recycling for iron slag with high valuable metal content; however, this method suffers from low metal recovery rates, the inability to recover the most abundant iron metal, and high production and processing costs, resulting in poor economic viability. The second is the use of iron slag with low valuable metal content for making building materials and microcrystalline glass, but this involves waste of metal resources and heavy metal leaching. The third method utilizes chemical and mineral processing methods to recover some valuable metals from the iron slag, but this generates new solid waste. The fourth method involves centralized stockpiling for treatment. None of the above methods achieve the recycling and reuse of iron-containing waste slag, which not only wastes mineral resources but also pollutes the surrounding environment. A large amount of funds need to be invested in comprehensive environmental management every year, which seriously affects the sustainable development of the mining economy. Utility Model Content

[0003] The purpose of this invention is to provide an improved rotary kiln for the efficient reduction of iron-containing waste slag, so as to solve the problems mentioned in the background art.

[0004] The technical solution of this utility model to achieve the above objectives is as follows:

[0005] An improved rotary kiln for efficient reduction of iron-containing waste slag, characterized in that it includes a feeding bin (1), a feeding screw conveyor (2), a flue gas hood (3), a kiln body (4), a kiln body support roller device (5), a kiln body transmission device (6), a kiln body baffle roller device (7), a discharge end sealing cover (8), a kiln inner wall insulation layer (9), a heating spray gun (10), and a discharge screw conveyor (11); the feeding bin (1) is connected to the inlet of the feeding screw conveyor (2), and the discharge end of the feeding screw conveyor (2) is sealed to the flue gas hood (3); the flue gas hood (3) The kiln tail end cover of the kiln body (4) is slidably sealed to the kiln head end cover of the kiln body (4) and the discharge end sealing cover (8) is slidably sealed to the discharge end sealing cover (8); the lower part of the discharge end sealing cover (8) is sealed to the feed inlet of the discharge screw conveyor (11), and the discharge end sealing cover (8) is equipped with a heating spray gun (10) inserted into the kiln body (4) on its front section; the kiln inner wall insulation layer (9) is composed of refractory brick layer in an angular spiral shape, and the outer wall of the kiln body (4) is a boiler steel structure; the troughs of the feeding screw conveyor (2) and the discharge screw conveyor (11) are both tubular structures.

[0006] According to the above-mentioned improved rotary kiln, the feeding chute of the feeding bin (1) is sealed to the tubular trough of the feeding screw conveyor (2), and the angle between the bottom edge of the feeding chute and the center line of the bin is 15-20°.

[0007] According to the above-mentioned improved rotary kiln, the discharge end of the feeding screw conveyor (2) is inserted into the kiln body (4) to a depth of 100-150mm, and the joint with the flue gas hood (3) is sealed by a flange.

[0008] According to the above-mentioned improved rotary kiln, the heating gun (10) is inserted at a position 5-10 mm above the center line of the kiln body (4) cross section, and the insertion depth is 150-200 mm.

[0009] According to the above-mentioned improved rotary kiln, the kiln body support roller device (5) is set on the upper circumferential surface of the kiln body (4), the kiln body baffle roller device (7) is symmetrically arranged on both sides of the lower part of the kiln body (4), and the kiln body transmission device (6) is installed on the outer wall of the middle part of the kiln body (4).

[0010] According to the above-mentioned improved rotary kiln, the spiral and the trough are made of 310S stainless steel.

[0011] According to the above-mentioned improved rotary kiln, the kiln body (4) is characterized by an installation inclination angle of 3-4°.

[0012] The technical advantages of this invention are as follows: Based on the characteristics of the roasting raw materials and the process features of high-temperature reduction roasting, the traditional rotary kiln has been structurally improved, resulting in a more efficient and improved rotary kiln for reduction. The improved rotary kiln has two main advantages: firstly, it achieves reduction roasting in a closed space, increasing the depth of reduction roasting; secondly, it alters the movement and trajectory of the roasting materials within the kiln, changing the original tumbling motion of the raw materials as the kiln rotates to a uniform, layered, and dispersed motion, thus accelerating the reduction roasting process. After the application of this improved rotary kiln, low-cost and highly efficient reduction roasting is achieved. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the device of this utility model;

[0014] Figure 2 This is a cross-sectional view of the rotary kiln body of this utility model. Detailed Implementation

[0015] The structure of this utility model will now be further described with reference to the accompanying drawings.

[0016] This utility model relates to an improved rotary kiln for the efficient reduction of iron-containing waste slag, the structure of which is as follows: Figure 1 As shown. The feeding hopper 1 is sealed to the tubular trough of the feeding screw conveyor 2 via a discharge chute. The bottom edge of the discharge chute is designed at a 15-20° angle to the center line of the hopper, allowing the material to slide naturally down the inclined surface into the conveyor under gravity. The feeding screw conveyor 2 uses a tubular trough and screw blades made of 310S stainless steel. Its discharge end is inserted into the kiln body 4 to a depth of 100-150mm, forming a closed channel through a flange seal connection with the flue hood 3, ensuring continuous material conveying while preventing flue gas leakage. See also... Figure 2 The kiln body 4 is composed of an outer boiler steel shell and an inner wall spiral refractory brick layer 9. Preferably, the spiral refractory brick structure forms a continuous wave-shaped protrusion on the cross-section, and the distance between adjacent protrusions is 1 / 6-1 / 5 of the inner diameter of the kiln body. When the kiln body rotates at an inclination angle of 3-4°, the material forms a layered cascading motion under the guidance of the wave-shaped protrusions, which significantly improves the contact efficiency between the reducing agent and the material.

[0017] The transmission system of the kiln body 4 includes a transmission device 6 installed on the middle outer wall, a support roller device 5 on the upper circumferential surface, and a baffle roller device 7 symmetrically arranged on both sides of the lower part. The three work together to ensure the stable rotation of the kiln body. The discharge end sealing cover 8 is connected to the kiln head end cover through an axial sliding guide rail. The high-temperature wear-resistant alloy layer welded on the surface of the guide rail can withstand long-term friction under operating conditions of 1400℃. The heating gun 10 is inserted into the kiln body from the front section of the sealing cover 8, with its tip located 5-10mm above the center line of the section and penetrating 150-200mm. This setting avoids the accumulation of materials and allows the flame to directly act on the core area of ​​the material flow. The sealing system adopts a multi-layer protection design. Preferably, a graphite packing sealing ring with an axial gap of 2-3mm is set between the flue gas hood 3 and the kiln tail end cover. The discharge port of the discharge end sealing cover 8 and the discharge screw conveyor 11 are dynamically sealed through a bellows to form a fully enclosed reduction environment.

[0018] The specific process is as follows: Material is fed by gravity from the feed hopper into the screw conveyor. The screw conveyor feeds the material into the kiln body. Due to the inclination and slow rotation of the kiln body, the material, driven by the kiln's reinforcing ribs, moves circumferentially and disperses while simultaneously moving axially from the kiln tail (feed end) to the kiln head (discharge end). Fuel (pulverized coal serves as both fuel and reducing agent) is injected into the kiln from the kiln head (feed end) through a burner for combustion. Heat is transferred through radiation, convection, and conduction. The calcination temperature is 120°C. At temperatures ranging from 0 to 1400℃, the material undergoes high-temperature reduction roasting during its movement. High-temperature volatile minerals such as lead and zinc in the material enter the flue gas. The flue gas is then transported by a dust collector to a dust collection device to recover the flue gas ash. The recovered flue gas is then sent by a fan to a flue gas treatment system for absorption and treatment. The resulting flue gas ash can be processed into a mixed lead and zinc oxide concentrate. Metallic iron, copper, and nickel enter the roasted sand. The roasted sand flows by gravity from the rotary kiln head into the discharge screw conveyor and is discharged. After cooling, the roasted sand is sent to the non-ferrous metal recovery and separation process. The main technical indicators of the products after roasting copper smelting slag tailings and nickel smelting converter slag using this equipment are shown in Tables 1 and 2.

[0019] Table 1. Statistical Table of Technical Indicators for Roasting Tailings from Copper Smelting Slag Beneficiation

[0020]

[0021]

[0022] Table 2. Statistical Table of Technical Indicators for Nickel Smelting Converter Slag Roasting

[0023]

[0024]

Claims

1. An improved rotary kiln for efficient reduction of iron-containing waste slag, characterized in that, The system includes a feeding hopper (1), a feeding screw conveyor (2), a flue gas hood (3), a kiln body (4), a kiln body support roller device (5), a kiln body transmission device (6), a kiln body retaining roller device (7), a discharge end sealing cover (8), a kiln inner wall insulation layer (9), a heating spray gun (10), and a discharge screw conveyor (11). The feeding hopper (1) is connected to the inlet of the feeding screw conveyor (2), and the discharge end of the feeding screw conveyor (2) is sealed to the flue gas hood (3). The flue gas hood (3) is connected to the kiln tail end cover of the kiln body (4). The kiln head end cover of the kiln body (4) is connected to the discharge end sealing cover (8) in a sliding seal connection; the lower part of the discharge end sealing cover (8) is connected to the feed inlet of the discharge screw conveyor (11) in a sealed connection, and a heating spray gun (10) inserted into the kiln body (4) is installed on the front section of the discharge end sealing cover (8); the heat insulation layer (9) of the kiln inner wall is constructed of refractory bricks in an angled spiral pattern, and the outer wall of the kiln body (4) is a boiler steel structure; the troughs of the feeding screw conveyor (2) and the discharge screw conveyor (11) are both tubular structures.

2. The improved rotary kiln according to claim 1, characterized in that, The discharge chute of the feeding bin (1) is sealed to the tubular trough of the feeding screw conveyor (2), and the angle between the bottom edge of the discharge chute and the center line of the bin is 15-20°.

3. The improved rotary kiln according to claim 1, characterized in that, The discharge end of the feeding screw conveyor (2) is inserted into the kiln body (4) to a depth of 100-150mm, and the connection with the flue gas hood (3) is sealed by a flange.

4. The improved rotary kiln according to claim 1, characterized in that, The heating gun (10) is inserted 5-10 mm above the center line of the kiln body (4) cross section, with an insertion depth of 150-200 mm.

5. The improved rotary kiln according to claim 1, characterized in that, The kiln body support roller device (5) is set on the upper circumferential surface of the kiln body (4), the kiln body baffle roller device (7) is symmetrically arranged on both sides of the lower part of the kiln body (4), and the kiln body transmission device (6) is installed on the outer wall of the middle part of the kiln body (4).

6. The improved rotary kiln according to claim 1, characterized in that, The spiral and the groove are made of 310S stainless steel.

7. The improved rotary kiln according to claim 1, characterized in that, The kiln body (4) is installed at an angle of 3-4°.

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