Process for producing very fine nickel carbonyl powder

Abstract

The application provides a preparation method of superfine carbonyl nickel powder, which utilizes a direct evaporation carbonyl nickel liquid mode, controls the carbonyl nickel mixed gas flow rate at the inlet of a decomposer by performing type selection design of a carbonyl nickel special nozzle, controls the carbonyl nickel evaporator temperature at 46-48 DEG C, controls the ratio of carbonyl nickel steam and CO gas to be 5-6:1, uses a DN325 diameter heated cavity nozzle, controls the carbonyl nickel flow rate sprayed into the decomposer to be 550-600 Kg / h, controls the temperature of the first four sections of the decomposer to be 400 DEG C-460 DEG C, and controls the temperature of the last three sections to be 220 DEG C-280 DEG C, so that the bulk specific gravity of the produced superfine carbonyl nickel powder is 0.8g / cm 3 The average particle size is below 1.0um, and the superfine carbonyl nickel powder meets the requirements of the military hard alloy field.

Description

Technical Field

[0001] This invention belongs to the field of industrial smelting technology and relates to a method for preparing ultrafine carbonyl nickel powder. Background Technology

[0002] The use of ultra-fine carbonyl nickel powder in the defense and military cemented carbide industry has long been monopolized by foreign companies. However, ultra-fine carbonyl nickel powder with special properties is an essential raw material for military cemented carbide materials. But producing ultra-fine carbonyl nickel powder with special properties poses a completely new challenge to the existing carbonyl nickel powder production process. Specifically, the existing production theories, such as the nucleation and directional growth theory of liquid decomposition of carbonyl nickel, the mixing technology of carbonyl nickel and CO, the temperature field control technology of carbonyl nickel decomposition, and the form of decomposition nozzle, are insufficient to guide the production of ultra-fine carbonyl nickel powder with special properties. It is necessary to achieve breakthroughs and applications in the key technologies for the production of ultra-fine carbonyl nickel powder with special properties based on the existing foundation. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the prior art by providing a method for preparing ultrafine carbonyl nickel powder. This method utilizes the introduction of CO gas to reduce the concentration of carbonyl nickel, combined with a nozzle device, to solve the problem of concentration segregation during the carbonyl nickel evaporation process in the production of ultrafine carbonyl nickel powder. It achieves uniform injection of a carbonyl nickel and CO mixture into the decomposer. Based on the carbonyl nickel decomposition theory, a carbonyl nickel decomposition temperature gradient is established, solving the problems of unstable powder morphology and difficulty in meeting the requirements of the central control product indicators during the production of ultrafine carbonyl nickel powder, thus achieving the successful production of ultrafine carbonyl nickel powder.

[0004] Therefore, the present invention adopts the following technical solution:

[0005] A method for preparing ultrafine carbonyl nickel powder includes the following steps:

[0006] Step a. The circulating hot water is heated by electric heating, and the temperature of the circulating hot water is controlled at 50-52℃. The carbonyl nickel liquid is evaporated by water bath, and the temperature of the carbonyl nickel evaporator is controlled at 46-48℃. This step uses hot water as the heat medium, which can ensure the heat required for system evaporation. At the same time, since hot water has a larger specific heat capacity, it further increases the stability of system evaporation and ensures stable system production.

[0007] Step b. The circulating hot water, with the temperature controlled at 50-52℃, causes the nickel carbonyl liquid in the evaporator to reach its boiling point, completing the evaporation of the nickel carbonyl liquid in the evaporator. The evaporated nickel carbonyl vapor is mixed with pure CO introduced at the evaporator outlet. Before entering the decomposer inlet pipe, the nickel carbonyl vapor and CO gas are uniformly mixed and stabilized. The mixing ratio of nickel carbonyl vapor to CO gas is 5-6:1, realizing the homogeneous decomposition of nickel carbonyl during the production process.

[0008] Step c. The uniformly mixed nickel carbonyl vapor and CO gas are passed through a DN325 heated cavity nozzle to reduce the mixing gas flow rate and further mix the nickel carbonyl vapor and CO gas. The mixture is then injected into the decomposer. The flow rate of nickel carbonyl injected into the decomposer is controlled at 550-600 kg / h to ensure that the mixed nickel carbonyl is further mixed and fully atomized before entering the decomposer, providing the basic conditions for nucleation reaction to occur after entering the decomposer.

[0009] Step d. The decomposer temperature during the production process is divided into 7 segments for decomposition. The decomposition process is that the mixed gas is thermally decomposed at different temperature gradients in a container heated by an external electric heater in a cylinder by adjusting the power opening.

[0010] The process involves seven temperature stages: 300℃-330℃ in the first stage, 325℃-345℃ in the second stage, 290℃-300℃ in the third stage, 280℃-295℃ in the fourth stage, 270℃-285℃ in the fifth stage, 260℃-265℃ in the sixth stage, and 230℃-245℃ in the seventh stage. This process ensures the complete decomposition of the nickel carbonyl vapor mixture in the decomposer and the nucleation of nickel crystals. This step establishes a multi-stage temperature gradient decomposition model. By establishing this model, the growth range of the nickel carbonyl crystals after the multi-stage reaction can be significantly improved, which plays an important role in the formation of the powder microstructure.

[0011] The beneficial effects of this invention are as follows:

[0012] 1. This invention provides a high-temperature evaporation and mixing process for nickel carbonyl, effectively solving the concentration segregation phenomenon in the vapor decomposition process of high-concentration nickel carbonyl, providing a production foundation for subsequent development, such as in the coating materials industry, and enabling the production of materials with a bulk ratio of 0.8 g / cm³. 3 The following particles have an average particle size of less than 1.0 μm, meeting the requirements for ultra-fine carbonyl nickel powder in the field of military cemented carbide.

[0013] 2. This invention establishes a temperature gradient model for the decomposition process of nickel carbonyl, clarifying the influence of temperature changes on the microstructure morphology of nickel carbonyl products, and can be promoted and applied in the research and development and production of other types of nickel carbonyl products. Attached Figure Description

[0014] Figure 1 The image shows the microstructure of the ultrafine carbonyl nickel powder prepared in Example 1 of this invention.

[0015] Figure 2 This is a microscopic morphology diagram of the ultrafine carbonyl nickel powder obtained in Example 2 of the present invention. Detailed Implementation

[0016] The technical solution of the present invention will be described below with reference to the accompanying drawings and implementation methods.

[0017] Example 1

[0018] A method for preparing ultrafine carbonyl nickel powder includes the following steps:

[0019] Step a. Heat the circulating hot water using electric heating, and control the temperature of the circulating hot water at 50-52℃. Evaporate the carbonyl nickel liquid using a water bath method, and control the temperature of the carbonyl nickel evaporator at 48℃.

[0020] Step b. The circulating hot water, with the temperature controlled at 50-52℃, causes the nickel carbonyl liquid in the evaporator to reach its boiling point, completing the evaporation of the nickel carbonyl liquid in the evaporator. The evaporated nickel carbonyl vapor is mixed with pure CO introduced at the evaporator outlet. The mixture from the evaporator outlet to the decomposer inlet pipe completes the uniform mixing and flow stabilization of the nickel carbonyl vapor and CO gas before entering the decomposer inlet. The mixing ratio of nickel carbonyl vapor to CO gas is 5:1.

[0021] Step d. The uniformly mixed nickel carbonyl vapor and CO gas are passed through a DN325 heated cavity nozzle to reduce the gas flow rate and further mix the nickel carbonyl vapor and CO gas. The mixture is then injected into the decomposer, and the flow rate of nickel carbonyl injected into the decomposer is controlled at 550-600 kg / h. The decomposer temperature is divided into 7 stages for decomposition during the production process. The decomposition process is carried out by thermal decomposition of the mixed gas in a container heated by an external electric heater in a cylindrical shell, with different temperature gradients achieved by adjusting the power opening.

[0022] The temperature ranges are as follows: the first stage is 330℃-345℃, the second stage is 345℃-360℃, the third stage is 330℃-350℃, the fourth stage is 295℃-310℃, the fifth stage is 285℃-290℃, the sixth stage is 270℃-260℃, and the seventh stage is 230℃-255℃. This process ensures the complete decomposition of the carbonyl nickel vapor mixture and the nucleation of nickel crystals in the decomposer. Figure 1 As shown, Example 1 produced carbonyl nickel powder with a bulk density of 0.67 g / cm³. 3 Average particle size 1.45um.

[0023] Example 2

[0024] A method for preparing ultrafine carbonyl nickel powder includes the following steps:

[0025] Step a. Heat the circulating hot water using electric heating, and control the temperature of the circulating hot water at 50-52℃. Evaporate the carbonyl nickel liquid using a water bath method, and control the temperature of the carbonyl nickel evaporator at 48℃.

[0026] Step b. The circulating hot water, with the temperature controlled at 50-52℃, causes the nickel carbonyl liquid in the evaporator to reach its boiling point, completing the evaporation of the nickel carbonyl liquid in the evaporator. The evaporated nickel carbonyl vapor is mixed with pure CO introduced at the evaporator outlet. The mixture from the evaporator outlet to the decomposer inlet pipe completes the uniform mixing and flow stabilization of the nickel carbonyl vapor and CO gas before entering the decomposer inlet. The mixing ratio of nickel carbonyl vapor to CO gas is 6:1.

[0027] Step d. The uniformly mixed nickel carbonyl vapor and CO gas are passed through a DN325 heated cavity nozzle to reduce the gas flow rate and further mix the nickel carbonyl vapor and CO gas. The mixture is then injected into the decomposer, with the flow rate of nickel carbonyl injected into the decomposer controlled at 580-600 kg / h. The decomposer temperature is divided into 7 stages for decomposition during the production process. The decomposition process is carried out by thermal decomposition of the mixed gas in a container heated by an external electric heater in a cylindrical shell, with different temperature gradients achieved by adjusting the power opening.

[0028] The temperature ranges are as follows: the first segment is 440℃-460℃, the second segment is 400℃-440℃, the third segment is 410℃-420℃, the fourth segment is 375℃-400℃, the fifth segment is 285℃-310℃, the sixth segment is 230℃-260℃, and the seventh segment is 210℃-235℃, ensuring stable system operation. Figure 2 As shown, Example 2 produced carbonyl nickel powder with a bulk density of 0.52 g / cm³. 3 Average particle size: 0.76 μm.

[0029] The above examples demonstrate that during the production of this type of ultrafine carbonyl nickel powder, the carbonyl nickel evaporation temperature should be controlled at 48℃, the mixing ratio of carbonyl nickel vapor to CO gas should be 6:1, and the thermal decomposition of carbonyl nickel should be carried out using a method of high temperature at the top and gradual temperature reduction. This method can successfully produce powder with a loose density of <1.0 g / cm³. 3 Extremely fine carbonyl nickel powder with an average particle size of <1.0 μm.

Claims

1. A method for preparing ultrafine carbonyl nickel powder, characterized in that, Includes the following steps: Step a. Heat the circulating hot water using electric heating, and control the temperature of the circulating hot water at 50-52℃. Evaporate the carbonyl nickel liquid using a water bath method, and control the temperature of the carbonyl nickel evaporator at 48℃. Step b. The circulating hot water, with the temperature controlled at 50-52℃, causes the nickel carbonyl liquid in the evaporator to reach its boiling point, completing the evaporation of the nickel carbonyl liquid in the evaporator. The evaporated nickel carbonyl vapor is mixed with pure CO introduced at the evaporator outlet. The mixture from the evaporator outlet to the decomposer inlet pipe completes the uniform mixing and flow stabilization of the nickel carbonyl vapor and CO gas before entering the decomposer inlet. The mixing ratio of nickel carbonyl vapor to CO gas is 6:

1. Step c. The uniformly mixed nickel carbonyl vapor and CO gas are passed through a DN325 heated cavity nozzle to reduce the gas flow rate and further mix the nickel carbonyl vapor and CO gas. The mixture is then injected into the decomposer, and the flow rate of nickel carbonyl injected into the decomposer is controlled at 550-600 kg / h. The decomposer temperature is divided into 7 stages for decomposition during the production process. The decomposition process is carried out by thermal decomposition of the mixed gas in a container heated by an external electric heater in a cylindrical shell, with different temperature gradients achieved by adjusting the power opening. The temperature ranges are as follows: the first stage is 440℃-460℃, the second stage is 400℃-440℃, the third stage is 410℃-420℃, the fourth stage is 375℃-400℃, the fifth stage is 285℃-310℃, the sixth stage is 230℃-260℃, and the seventh stage is 210℃-235℃. This process ensures the complete decomposition of the carbonyl nickel vapor mixture in the decomposer and the nucleation of nickel crystals.

2. The method for preparing ultrafine carbonyl nickel powder according to claim 1, characterized in that, The diameter of the nozzle in the heat tracing chamber is DN325.

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