A method for preparing pellets from South African copper tailings powder

Abstract

The invention discloses a method for preparing pellets from all-South African copper tailings powder, comprising the steps of high-pressure roller grinding, mixing ingredients, pelletizing, material screening, drying and preheating, roasting, cooling of pellets, etc. The method of the invention improves the utilization rate of the South African copper tailings powder, and ensures the quality of the finished pellets by appropriately increasing the pre-roasting temperature and the roasting temperature. The average compressive strength of the pellets is ≥2500N / ball, the expansion index is ≤15%, the drum index is ≥92%, and the ‑5mm ratio is ≤5%.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a method for preparing pellets from all-South African copper tailings powder. Background Art

[0002] South African copper tailings powder has high iron grade, high titanium, phosphorus and copper content, low price, but poor sintering performance. If South African copper tailings powder can be used in pellet production in large quantities, it will not only make comprehensive use of tailings, but also greatly reduce production costs.

[0003] Due to the poor sintering performance of South African copper tailings powder, it can only be added in small quantities when applied to the sintering system. For example, Hesteel Chenggang and Hesteel Handan Iron and Steel have used it in sintering ore, but the ratio was less than 20%.

[0004] The School of Metallurgy and Energy of North China University of Technology conducted research on the use of South African copper tailings powder for pellet preparation, which was also limited to the ratio of South African copper tailings powder between 0.65-0.8, and the rest was added with Sijiaying ore powder.

[0005] Therefore, it is necessary to develop a method for preparing pellets from South African copper tailings powder so that the South African copper tailings powder can be fully utilized. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing pellets from South African copper tailings powder.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing pellets from all-South African copper tailings powder, comprising the following steps:

[0009] 1) High-pressure roller mill: granulate the South African copper tailings powder to -200 mesh>70%;

[0010] 2) Batching: Add bentonite to the South African copper tailings powder, the amount of bentonite is 1-2%, and the rest is all South African copper tailings powder. After batching, use a high-powered mixer to mix;

[0011] 3) Ball making: Use a disc ball making machine to add appropriate amount of water during the ball making process, so that the moisture content of the raw balls is controlled at 8.5-10%, the inclination angle of the ball making disc is 45-49°, the speed of the ball making disc is 7-8r / min, and the particle size of the raw balls is 8-20mm;

[0012] 4) Material screening: The green pellets are screened to obtain green pellets with a particle size of 8.5-16.5mm, and then enter the chain grate with a material thickness of 150-180mm;

[0013] 5) Drying and preheating: Control the chain grate technology at 2-2.6m / min. The green balls enter the chain grate for drying. The first stage drying temperature is 60-150℃, and the second stage drying temperature is 250-400℃. Dry until the moisture content of the green balls drops below 5%, and then enter the preheating treatment. The first stage preheating temperature is controlled at 700-900℃, and the second stage preheating temperature is controlled at 1050-1080℃.

[0014] 6) Calcination: Control the kiln speed at 0.7-0.85rpm. After the finished pellets are dried, dehydrated, preheated and oxidized in the grate, they are then sent to the rotary kiln for calcination. The temperature is controlled at 1290-1330℃.

[0015] 7) Ball cooling: The finished pellets are then cooled to below 50°C on a ring cooler and discharged from the ring cooler to obtain South African copper tailings powder pellets.

[0016] Preferably, the bentonite montmorillonite is ≥ 60%.

[0017] The technical solution of the present invention has the following beneficial technical effects:

[0018] The method of the present invention improves the utilization rate of South African copper tailings powder and reduces the pellet cost; by appropriately increasing the pre-baking temperature and the baking temperature, the quality of the finished pellets is guaranteed, which is beneficial to the pellet forming rate and the overall strength of the pellets.

[0019] The all-South African copper tailings powder pellets provided by the invention have an average compressive strength of ≥2500N / ball, a swelling index of ≤15%, a drum index of ≥92%, and a -5mm ratio of ≤5%, which fully meet the production requirements of blast furnaces. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solution of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Example 1

[0022] A method for preparing pellets from all-South African copper tailings powder, comprising the following steps:

[0023] 1) High-pressure roller mill: granulate the South African copper tailings powder to -200 mesh to reach 80%;

[0024] 2) Batching: Add bentonite to the South African copper tailings powder for batching, the bentonite dosage is 1.6% (the bentonite montmorillonite content is 65%), and the remaining 98.4% is the South African copper tailings powder. After batching, use a high-powered mixer to mix to form a mixture;

[0025] 3) Ball making: Use a disc ball making machine to add appropriate amount of water during the ball making process to control the moisture content of the raw balls at 9%, the inclination angle of the ball making disc is 47°, the speed of the ball making disc is 7.5r / min, and the particle size of the raw balls is 10mm;

[0026] 4) Material screening: The green pellets are screened to obtain green pellets with a particle size of 10 mm, and then enter the chain grate with a material thickness of 175 mm;

[0027] 5) Drying and preheating: Control the speed of the chain grate at 2.3m / min. The green balls enter the chain grate for drying. The first stage drying temperature is 100℃, and the second stage drying temperature is 350℃. Dry until the moisture content of the green balls drops to 3%. Then enter the preheating process. The first stage preheating temperature is controlled at 800℃, and the second stage preheating temperature is controlled at 1065℃.

[0028] 6) Calcination: The kiln speed is controlled at 0.8rpm. The finished pellets are dried, dehydrated, preheated and oxidized in the grate, and then enter the rotary kiln for calcination. The temperature is controlled at 1310℃.

[0029] 7. Ball cooling: The finished pellets are then cooled to 40°C on a ring cooler and discharged from the ring cooler to obtain South African copper tailings powder pellets.

[0030] The average compressive strength of the South African copper tailings powder pellets is 2749N / ball, the expansion index is 13.2%, the drum index is 93.5%, and the -5mm ratio is 3.3%, which fully meets the requirements of blast furnace production. Example 2

[0031] A method for preparing pellets from all-South African copper tailings powder, comprising the following steps:

[0032] 1) High-pressure roller mill: granulate the South African copper tailings powder to -200 mesh to reach 85%;

[0033] 2) Batching: Add bentonite to the South African copper tailings powder for batching, the bentonite dosage is 2% (bentonite montmorillonite content is 60%), and the remaining 98% is South African copper tailings powder. After batching, use a high-powered mixer to mix to form a mixture;

[0034] 3) Ball making: Use a disc ball making machine to add appropriate amount of water during the ball making process to control the moisture content of the raw balls at 10%, the inclination angle of the ball making disc is 49°, the speed of the ball making disc is 8r / min, and the particle size of the raw balls is 20mm;

[0035] 4) Material screening: The green pellets are screened to obtain green pellets with a particle size of 16.5 mm, and then enter the chain grate with a material thickness of 180 mm;

[0036] 5) Drying and preheating: Control the speed of the chain grate at 2.6m / min. The green balls enter the chain grate for drying. The first stage drying temperature is 150℃, and the second stage drying temperature is 400℃. Dry until the moisture content of the green balls drops to 2%. Then enter the preheating process. The first stage preheating temperature is controlled at 900℃, and the second stage preheating temperature is controlled at 1080℃.

[0037] 6) Calcination: The kiln speed is controlled at 0.85rpm. After the finished pellets are dried, dehydrated, preheated and oxidized in the grate, they are sent to the rotary kiln for calcination. The temperature is controlled at 1330℃.

[0038] 7) Ball cooling: The finished pellets are then cooled to 50°C on a ring cooler and discharged from the ring cooler to obtain South African copper tailings powder pellets.

[0039] The average compressive strength of the South African copper tailings powder pellets is 2685N / ball, the expansion index is 12.8%, the drum index is 94.3%, and the -5mm ratio is 3.4%, which fully meets the requirements of blast furnace production. Example 3

[0040] A method for preparing pellets from all-South African copper tailings powder, comprising the following steps:

[0041] 1) High-pressure roller mill: granulate the South African copper tailings powder to -200 mesh to reach 72%;

[0042] 2) Batching: Add bentonite to the South African copper tailings powder, the bentonite dosage is 1% (the bentonite montmorillonite content is 75%), and the remaining 99% is the South African copper tailings powder. After batching, use a high-powered mixer to mix to form a mixture;

[0043] 3) Ball making: Use a disc ball making machine to add appropriate amount of water during the ball making process to control the moisture content of the raw balls at 8.5%, the inclination angle of the ball making disc is 45°, the speed of the ball making disc is 7r / min, and the particle size of the raw balls is 8mm;

[0044] 4) Material screening: The green pellets are screened to obtain green pellets with a particle size of 8.5 mm, and then enter the chain grate with a material thickness of 150 mm;

[0045] 5) Drying and preheating: Control the speed of the chain grate machine at 2m / min. The green balls enter the chain grate machine for drying. The first stage drying temperature is 60℃, and the second stage drying temperature is 250℃. Dry until the moisture content of the green balls drops to 5%. Then enter the preheating process. The first stage preheating temperature is controlled at 700℃, and the second stage preheating temperature is controlled at 1050℃.

[0046] 6) Calcination: The kiln speed is controlled at 0.7rpm. After the finished pellets are dried, dehydrated, preheated and oxidized in the grate, they are sent to the rotary kiln for calcination. The temperature is controlled at 1290℃.

[0047] 7) Ball cooling: The finished pellets are then cooled to 35°C on a ring cooler and discharged from the ring cooler to obtain South African copper tailings powder pellets.

[0048] The average compressive strength of the South African copper tailings powder pellets is 2713N / ball, the expansion index is 12.4%, the drum index is 93.6%, and the -5mm ratio is 3.2%, which fully meets the requirements of blast furnace production.

[0049] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0050] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing pellets from all-South African copper tailings powder, characterized in that: The following steps are involved: 1) High-pressure roller mill: granulate the South African copper tailings powder to -200 mesh>70%; 2) Batching: Add bentonite to the South African copper tailings powder for batching, the bentonite dosage is 1-2%, and the rest is all South African copper tailings powder, and the ingredients are mixed with a powerful mixer after batching; 3) Ball making: Use a disc ball making machine to add appropriate amount of water during the ball making process, so that the moisture content of the raw balls is controlled at 8.5-10%, the inclination angle of the ball making disc is 45-49°, the speed of the ball making disc is 7-8r / min, and the particle size of the raw balls is 8-20mm; 4) Material screening: The green pellets are screened to obtain green pellets with a particle size of 8.5-16.5 mm, and then enter the chain grate with a material thickness of 150-180 mm; 5) Drying and preheating: Control the speed of the chain grate machine at 2-2.6m / min, and the green balls enter the chain grate machine for drying. The first stage drying temperature is 60-150℃, and the second stage drying temperature is 250-400℃. Dry until the moisture content of the green balls drops below 5%, and then enter the preheating process. The first stage preheating temperature is controlled at 700-900℃, and the second stage preheating temperature is controlled at 1050-1080℃; 6) Calcination: Control the kiln speed at 0.7-0.85rpm. After the finished pellets are dried, dehydrated, preheated and oxidized in the grate, they are then roasted in the rotary kiln at a controlled temperature of 1290-1330℃. 7) Ball cooling: The finished pellets are then cooled to below 50°C on a ring cooler and discharged from the ring cooler to obtain South African copper tailings powder pellets.

2. The method for preparing pellets from all-South African copper tailings powder according to claim 1, characterized in that: The bentonite montmorillonite is ≥ 60%.

3. The method for preparing pellets from all-South African copper tailings powder according to claim 1, characterized in that: The South African copper tailings powder pellets prepared by the method have an average compressive strength of ≥2500N / ball, a swelling index of ≤15%, a drum index of ≥92%, and a -5mm ratio of ≤5%.