Method for preparing iron oxide red by using supergravity machine

Abstract

In order to solve the problems of long time consumption and high cost in the existing production of iron oxide red, the invention provides a method for preparing iron oxide red by using a by-product ferrous sulfate obtained by producing titanium dioxide in combination with a supergravity machine, which comprises the following steps of: dissolving the titanium dioxide by-product ferrous sulfate with the weight of A in water with the weight of B under the stirring action at normal temperature; adjusting the pH value of the ferrous sulfate solution to 4-5 through an alkaline liquid; putting the obtained solution into a supergravity machine, stirring and oxidizing, and sequentially carrying out solid-liquid separation, washing and drying on the oxidized ferrous acid solution to obtain solid ferric oxide; and finally drying in a drying oven to obtain the iron oxide red. According to the iron oxide red prepared by the method, the content of impurity sulfur is remarkably reduced while high specific surface and high activity of the iron oxide red are reserved; and the oxidation time is greatly saved, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of red iron oxide preparation, and in particular to a method for preparing red iron oxide by using a supergravity machine. Background Art

[0002] As a new type of green high-energy chemical power source, lithium-ion batteries have many significant advantages, including high operating voltage, high specific energy, long cycle life, low self-discharge rate, no memory effect, and environmental friendliness. However, the defects of traditional lithium-ion battery cathode materials, such as lithium cobalt oxide, lithium manganese oxide, and ternary materials, in terms of price, safety, and cycle performance have always hindered the development and application of lithium-ion batteries in high-power power battery fields such as new energy vehicles and power tools.

[0003] In contrast, lithium iron phosphate materials are recognized as the preferred cathode material for the new generation of lithium-ion power batteries due to their good safety, excellent cycle performance, environmental friendliness, and abundant raw material resources, and have become the research focus and development direction of countries around the world. However, the iron sources currently used to prepare lithium iron phosphate materials, such as iron phosphate, ferrous oxalate, and iron oxide prepared by co-precipitation, are relatively expensive, resulting in excessively high costs for lithium iron phosphate, which has hindered the expansion of its market.

[0004] With the continuous development of the new energy industry, the demand for high-performance, low-cost cathode materials is increasing. As a potential source of lithium iron phosphate, red iron oxide has broad application prospects. By improving the preparation process of red iron oxide and increasing its purity, its performance in lithium iron phosphate can be further improved.

[0005] Chinese patent CN109437321B discloses a method for producing red iron oxide using ferrous sulfate heptahydrate, a byproduct of titanium dioxide. Although the method improves work efficiency to a certain extent, the continuous air input is required by a blower during the use of the supergravity machine, which not only reduces the overall reliability of the equipment, but also increases the cost.

[0006] Therefore, how to prepare red iron oxide and lower its production cost has become a technical problem that needs to be urgently solved by technicians in this field. Summary of the invention

[0007] In order to solve the problem that the existing production of red iron oxide is time-consuming and costly, the present invention provides a method for preparing red iron oxide by utilizing ferrous sulfate, a byproduct obtained from the production of titanium dioxide, in combination with an ultra-gravity machine. The method has high efficiency in producing red iron oxide, excellent product quality, and greatly reduces production costs.

[0008] A method for preparing red iron oxide using a supergravity machine comprises the following steps:

[0009] S100: At room temperature, dissolve ferrous sulfate by-product of titanium dioxide with a weight of A in water with a weight of B under stirring, where the ratio of A to B is 1:1.7 to 1:2;

[0010] S200: After complete dissolution, separate by filtration to remove impurities and obtain a ferrous sulfate solution;

[0011] S300: Adjust the pH value of the ferrous sulfate solution with an alkaline liquid and adjust its pH value to between 4 and 5;

[0012] S400: Put the solution obtained in S300 into a high-gravity machine for stirring oxidation. The high-gravity machine includes a first stirring unit and a second stirring unit connected to each other, where the second stirring unit is used to adjust the pH value of the ferrous sulfate solution;

[0013] S500: Perform solid-liquid separation, washing, and drying on the ferrous sulfate solution after S400 is completed to obtain solid iron oxide;

[0014] S600: Put the solid iron oxide obtained in S500 into an oven for drying to obtain iron oxide red.

[0015] Further, the temperature of the oven is 56°C to 63°C.

[0016] Further, the alkaline liquid includes an ammonium bicarbonate solution.

[0017] Further, the high-gravity machine includes a high-gravity machine body, and a first stirring unit is arranged inside the high-gravity machine body; it also includes a first storage bucket and a second storage bucket connected to the high-gravity machine body, and a second stirring unit and a pH measuring device are arranged inside the second storage bucket.

[0018] In the present invention, a first stirring unit and a second stirring unit are arranged to be connected to each other through a high-gravity machine, where the second stirring unit is used to adjust the pH value of the ferrous sulfate solution, greatly increasing the contact area between the slurry and oxygen and shortening the oxidation time. Under the same experimental dosage and experimental method, about 40% of the time can be saved. And the iron oxide red prepared by the present invention, while retaining the high specific surface area and high activity of the iron oxide red, significantly reduces the impurity sulfur content; the D50 of the prepared iron oxide red is 10 - 12 μm, the BET is 4 - 6 m2 / g, and the sulfur content is 0.02% - 0.05%. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the high-gravity machine related to the present invention.

[0020] Reference Signs:

[0021] 110 ultra-gravity machine body, 111 first stirring unit, 120 second storage barrel, 121 second stirring unit, 122 PH measuring device, 130 first storage barrel. DETAILED DESCRIPTION

[0022] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0023] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection of two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0024] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0025] In the description of this specification, titanium dioxide by-product ferrous sulfate refers to the by-product ferrous sulfate obtained in the production of titanium dioxide.

[0026] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0027] like Figure 1 As shown, the method for preparing red iron oxide using a supergravity machine comprises the following steps:

[0028] S100: At room temperature, dissolve titanium white by-product ferrous sulfate with a weight of A in water with a weight of B under stirring, where the ratio of A to B is 1:1.7 to 1:2. Selecting room temperature in the present invention can avoid energy consumption and possible side reactions caused by high temperature, and ensure the stability and controllability of the dissolution process. In a specific implementation, 11.1 kg of ferrous sulfate is incorporated into 20 kg of water by stirring.

[0029] S200: After complete dissolution, separate by filtration to remove impurities. A commonly used filtration separation method in the prior art can be selected to remove insoluble impurities, thereby obtaining a pure ferrous sulfate solution.

[0030] S300: Adjust the pH value of the ferrous sulfate solution with an alkaline liquid, for example, using ammonium bicarbonate solution to adjust the pH value to between 4 and 5. In this embodiment, ammonium bicarbonate solution is used as an alkaline regulator, which can provide a carbon source during the oxidation process and promote the formation of iron oxide red.

[0031] S400: Put the solution obtained in S300 into a high-gravity machine for stirring oxidation. The high-gravity machine includes a first stirring unit 111 and a second stirring unit 121 connected to each other, where the second stirring unit 121 is used to adjust the pH value of the ferrous sulfate solution.

[0032] In the present invention, the ferrous sulfate solution after pH adjustment is transferred to a high-gravity machine, and the circulating stirring function of the high-gravity machine is used to allow the material to fully contact with oxygen. During this process, a hydrogen peroxide solution equivalent to 3 wt% of ferrous sulfate can also be dropped in to accelerate the oxidation rate. During the oxidation process, the change of the pH value is continuously monitored. When the pH value drops below 3, the pH value is adjusted to the range of 3.8 - 4 with ammonium bicarbonate solution, and the cycle is repeated until the pH value no longer changes significantly, indicating the end of the oxidation synthesis reaction.

[0033] In the present invention, the high gravity machine includes a high gravity machine body 110, and a first stirring unit 111 is arranged inside the high gravity machine body 110; it further includes a first storage barrel 130 and a second storage barrel 120 which are connected to the high gravity machine body 110 through pipelines. Both the first storage barrel 130 and the second storage barrel 120 are open storage barrels and can be directly communicated with the air; the ferrous sulfate solution flows into the second storage barrel 120 from the high gravity machine body 110 through a pipeline, and stirring and pH value adjustment are carried out in the second storage barrel 120. When the pH value is shown to be lower than 3, an alkali solution is used to adjust the pH value of the ferrous sulfate solution back to 3.8 - 4 until the pH value remains unchanged in this range, then the stirring is stopped, and the adjusted ferrous sulfate solution is transported to the first storage barrel 130 for storage through a pipeline, and then returned from the first storage barrel 130 to the high gravity machine body 110. In this way, the mixing of the alkali solution and the ferrous sulfate solution can be made more uniform, avoiding local over-alkalinity. In the present invention, the first storage barrel 130 can be physically higher than the high gravity machine body 110, and the ferrous sulfate solution flows into the high gravity machine body 110 by gravity.

[0034] The high gravity machine adopted in the present invention can greatly increase the contact area between the ferrous sulfate solution and oxygen, shorten the oxidation time. Under the same experimental dosage and experimental method, the high gravity machine adopted in the present invention can shorten the oxidation time from the existing 40 hours to 24 hours, saving about 40% of the time, overcoming the problem of too long time-consuming of the air oxidation method, reducing the production energy consumption. At the same time, the high gravity machine adopted in the present invention has strong motive power, and also overcomes the problem of the increase in stirring resistance caused by the thickening of the system during the reaction of the ferrous sulfate solution.

[0035] S500: The ferrous sulfate solution after S400 is subjected to solid-liquid separation, washing, and drying in sequence to obtain solid iron oxide; through solid-liquid separation, solid iron oxide and liquid can be effectively separated, improving the product yield; through washing, impurities attached to the surface of the solid iron oxide can be removed, improving the product purity; through drying, moisture can be removed to obtain solid iron oxide, which is convenient for subsequent treatment and storage.

[0036] S600: The solid iron oxide obtained in S500 is put into an oven for drying to obtain iron oxide red. In the present invention, the oven temperature is controlled at 56°C to 63°C to ensure the stable formation of iron oxide red. The oven temperature is controlled at 60°C with the best effect, avoiding structural changes or decomposition caused by too high temperature; the drying process further removes residual moisture, improves the dryness and stability of iron oxide red, and optimizes the quality and performance of the final product.

[0037] In summary, the present invention exhibits remarkable effects in various processes such as dissolution, filtration, pH adjustment, oxidation, solid-liquid separation, washing, drying, and baking. The iron oxide red prepared by the present invention, while retaining the high specific surface area and high activity of iron oxide red, significantly reduces the sulfur content of impurities. The D50 of the prepared iron oxide red is 10 - 12 μm, the BET is 4 - 6 m2 / g, and the sulfur content is 0.02% - 0.05%.

[0038] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing iron oxide red by using a high gravity mechanism, characterized in that, It includes the following steps: S100: At room temperature, dissolve titanium white by-product ferrous sulfate weighing A in water weighing B under stirring, where the ratio of A to B is 1:1.7 to 1:2; S200: After complete dissolution, separate by filtration to remove impurities and obtain a ferrous sulfate solution; S300: Adjust the pH value of the ferrous sulfate solution with an alkaline liquid to adjust its pH value to between 4 and 5; S400: Put the solution obtained in S300 into a high gravity machine for stirring oxidation. The high gravity machine includes a first stirring unit (111) and a second stirring unit (121) connected to each other, where the second stirring unit (121) is used to adjust the pH value of the ferrous sulfate solution; S5 S500: Perform solid-liquid separation, washing, and drying on the ferrous sulfate solution after S400 is completed to obtain solid iron oxide; S600: Put the solid iron oxide obtained in S500 into an oven for drying to obtain iron oxide red.

2. The method for preparing iron oxide red by using a supergravity mechanism according to claim 1, characterized in that: The temperature of the oven is 56°C to 63°C.

3. The method for preparing iron oxide red by using a high gravity machine according to claim 1 or 2, characterized in that: The alkaline liquid includes an ammonium bicarbonate solution.

4. The method for preparing iron oxide red by using high gravity according to claim 1 or 2, characterized in that: The high gravity machine includes a high gravity machine body (110) with a first stirring unit (111) arranged inside; it also includes a first storage tank (130) and a second storage tank (120) connected to the high gravity machine body (110), and a second stirring unit (121) and a pH measuring device (122) are arranged inside the second storage tank (120).

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