Process for preparing an alcohol-paraffin mixture

Abstract

The present application relates to the field of powder metallurgy method, and particularly relates to a novel alcohol paraffin mixture preparation process, which comprises the following steps: melting paraffin into liquid, atomizing the paraffin into small paraffin droplets, contacting the small paraffin droplets with cooling gas in a tower to rapidly cool the small paraffin droplets into round paraffin powder; carrying out dry premixing of a set amount of paraffin powder used as a forming agent and raw materials prepared according to component proportioning for a preset mixing duration; adding the mixture of the paraffin powder and the raw materials uniformly mixed into a ball mill, adding alcohol according to preset requirements, and carrying out ball milling according to grinding conditions. The present application can guarantee uniform granular paraffin powder before ball milling, so that the paraffin powder is more uniformly distributed during ball milling.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy methods, and more specifically to a process for preparing an alcohol-paraffin mixture. Background Technology

[0002] Hexane is widely used in the field of chemical organic synthesis. However, due to its anesthetic and irritant properties, long-term exposure can lead to peripheral neuritis, headaches, dizziness, lower limb weakness, muscle atrophy, and other dangerous conditions, posing a significant risk to human health. Hexane is also highly flammable; its vapor can form an explosive mixture with air, readily igniting and exploding upon contact with open flames or high heat. In addition to these chemical hazards, in the ball milling process for mixed materials, hexane's low density and poor wettability with tungsten carbide, the main raw material, result in poor suspension of tungsten carbide in hexane, significantly reducing the grinding efficiency of wet milling. In contrast, alcohol, as a wet milling medium, poses relatively less harm to the human body upon direct contact, has lower equipment safety requirements than hexane, and exhibits better wettability with tungsten carbide, improving the suspension of raw material powder, significantly increasing grinding efficiency, and resulting in better uniformity of the mixture.

[0003] When polyethylene glycol (PEG) is used as a molding agent, it is not completely miscible with pure alcohol, but it is completely soluble in alcohol with a purity of 92% or lower. When using PEG, water must be added to adjust the alcohol purity to below 92%, as water easily causes oxidation of the raw materials. PEG is hygroscopic; after absorbing moisture, the mixed particles harden, resulting in poor pressing performance and difficulty in compact forming. PEG is emitted during sintering via hydrogen combustion, and cannot be recycled, easily causing environmental pollution. Paraffin wax, when used as a molding agent, can be completely vaporized below 550℃ during sintering, without causing significant fluctuations in the carbon content of the alloy product; moreover, paraffin wax can be recycled during sintering, without causing environmental pollution.

[0004] The alcohol-paraffin process, also known as the ball milling media-paraffin mixture preparation process, involves using alcohol as the grinding medium and paraffin as the forming agent. For example, patent document CN101514405A discloses a method for preparing a cemented carbide mixture. The raw materials include WC powder, WC-TiC solid solution, and Co powder. Paraffin is used as the forming agent, anhydrous alcohol as the grinding medium, and oleic acid and stearic acid are added as dispersants to the grinding medium. The process includes: a precise batching step, where heated, melted, and filtered paraffin is pre-ground in a ball mill; a wet grinding step, where the prepared material is loaded into the ball mill cylinder with an appropriate amount of alcohol as the grinding medium and a dispersant, followed by wet grinding; a slurry filtration step, where the slurry is discharged and filtered through a 200-320 mesh filter; a spray drying and granulation step, where the slurry is spray-dried and granulated using spray drying equipment; and a sieving step, producing mixed granules suitable for various pressing requirements. This method has a short production process, stable and reliable product quality, high production efficiency, and is suitable for large-scale production operations. It can be widely used in the preparation of cemented carbide mixtures.

[0005] However, because alcohol and paraffin are completely immiscible, the uneven distribution of paraffin in the mixture can easily lead to pores and dimensional fluctuations in alloy products, affecting the quality stability of the alloy products. Therefore, how to avoid the formation of large paraffin particles and paraffin aggregation has become the most critical challenge in the preparation process of alcohol-paraffin mixture. Summary of the Invention

[0006] The present invention aims to provide a process for preparing an alcohol-paraffin mixture to solve the problems of immiscibility and uneven distribution of paraffin during the preparation of an alcohol-paraffin mixture.

[0007] The novel alcohol-paraffin mixture preparation process in this scheme includes:

[0008] Step 1: After melting the paraffin wax into a liquid, atomize the paraffin wax into small droplets. In the tower, let the small droplets of paraffin wax come into contact with the cooling gas and cool them rapidly into round paraffin wax powder.

[0009] Step 2: Dry premix the set amount of paraffin powder used as a molding agent with the raw materials prepared according to the component ratio for a preset mixing time.

[0010] Step 3: Add the mixture of paraffin powder and raw materials evenly into the ball mill, add the preset amount of alcohol, and ball mill according to the grinding conditions.

[0011] The beneficial effects of this plan are:

[0012] During the preparation of the mixture, the paraffin wax is atomized and immediately cooled to form spherical paraffin wax powder. Before ball milling, the paraffin wax powder is dry premixed with the raw materials and then ball milled. This ensures that the paraffin wax powder has a uniform particle shape before ball milling and allows the paraffin wax powder to be distributed more evenly during ball milling.

[0013] Furthermore, in step 1, when the paraffin is atomized, an open or closed spray device is used to spray the paraffin liquid in a centrifugal or pressure manner. The pressure spray pressure is 100-2000 kPa, and the centrifugal atomizer speed is 1000-15000 rpm.

[0014] The beneficial effects are: the atomization of paraffin wax facilitates corresponding adjustments, the process operation during production is flexibly controlled, and the setting of pressure and speed can precisely control the particle size of paraffin wax particles. The higher the pressure, the better the atomization and dispersion of paraffin wax, and the finer the particle size of the produced paraffin wax particles. The higher the centrifugal speed, the better the atomization and dispersion of paraffin wax, the finer the particle size of the produced paraffin wax particles, and the smaller and more uniform the atomized droplets.

[0015] Furthermore, in step 1, cooling gas within a preset temperature range is continuously input to contact the paraffin droplets, and the temperature inside the tower is kept below 30°C, wherein the preset temperature range is below 25°C.

[0016] The beneficial effects are: after the paraffin is atomized, cooling gas is immediately introduced. Through the temperature control inside the tower and the temperature control of the cooling gas, the small droplets of paraffin can be quickly solidified to form paraffin powder particles, and the paraffin powder particles are more uniform and maintain their state for a longer period of time.

[0017] Furthermore, in step 2, the raw materials are added to a mixing device such as a double cone mixer, a Z-type mixer, or a double spiral mixer for dry premixing. The cylinder of the dry premixing device rotates at a speed of 5-200 rpm, the stirring shaft rotates at a speed of 5-300 rpm, and the preset mixing time is 0.2-24 hours.

[0018] The beneficial effects are: by using a mixing device to dry premix the raw materials under certain conditions, the raw materials can be mixed quickly when they enter the mixing device, which can prevent the excessive extrusion pressure between particles during dry premixing from causing particle breakage before ball milling, and make the raw materials more uniformly mixed.

[0019] Furthermore, in step 2, the temperature of the inner cavity of the mixing device is controlled to keep the inner cavity temperature within the range of -30℃ to 50℃.

[0020] The beneficial effects are: the temperature of the mixing device cylinder is effectively controlled, preventing the paraffin powder from liquefying due to high temperature during operation and affecting its mixing uniformity.

[0021] Furthermore, in step 2, a cooling medium is introduced into the inner cavity of the jacket layer of the mixing device cylinder for temperature control, or the surface of the cylinder of the mixture is directly in contact with the cooling medium for temperature control, wherein the temperature of the cooling medium is in the range of less than 25°C.

[0022] The beneficial effects are: by controlling the temperature of the cooling medium on the outer wall of the mixed body, the temperature control is more direct and faster, and the liquefaction of paraffin powder particles is prevented from affecting the uniformity of mixing.

[0023] Furthermore, in step 3, during the ball milling process, the temperature inside the mill is controlled by introducing a cooling medium into the jacket cavity of the ball mill, and the temperature of the cooling medium is within the range of less than 25°C.

[0024] The beneficial effects are: effective temperature control of the ball mill cylinder, preventing the temperature inside the ball mill from rising and causing paraffin liquefaction and segregation, thus ensuring the effectiveness of ball milling.

[0025] Furthermore, in step 3, a temperature probe is installed on the end cover of the ball mill to monitor the internal temperature in real time. The goal is to control the internal temperature to be less than a preset value. The internal temperature is judged to be 90% of the preset value. When the internal temperature reaches 90% of the preset value, the amount of cooling medium introduced into the jacket cavity of the ball mill is controlled.

[0026] The beneficial effects are: setting a control target for the internal temperature of the ball mill, and controlling the cooling medium when the internal temperature of the ball mill is about to reach the control target, thus improving the timeliness of internal temperature control and ensuring that the paraffin particles inside the ball mill will not melt due to high temperature and cause segregation.

[0027] Furthermore, in step 3, the preset requirement is that the alcohol density is less than or equal to 0.82 g / cm³, and the grinding conditions are based on total quantity control, with the solid-liquid mass ratio in the ball milling process set between 85:15 and 75:25.

[0028] The beneficial effects are: the preset alcohol content can better control the oxygen content of the material, the carbon content of the mixture, and the consistency of grinding efficiency; the grinding conditions can ensure the consistency of slurry viscosity and filling coefficient, thereby ensuring the consistency of grinding efficiency. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating an embodiment of the preparation process of the novel alcohol-paraffin mixture of the present invention. Detailed Implementation

[0030] The following detailed description provides further details on specific implementation methods.

[0031] Example

[0032] Novel alcohol-paraffin mixture preparation process, such as Figure 1 As shown, it includes:

[0033] Step 1: After melting the paraffin wax into a liquid, atomize it into small droplets. When atomizing the paraffin wax, use an open or closed spraying device. Select an existing product according to the needs, such as the BP25 closed spray drying tower. Atomize the paraffin wax liquid using centrifugal or pressure methods. The pressure spraying pressure is 100-2000 kPa, and the centrifugal atomizer speed is 1000-15000 rpm.

[0034] Cooling gas, such as air, nitrogen, or argon, is injected into the tower. Inside the tower, small paraffin droplets come into contact with the cooling gas, rapidly cooling them into spherical paraffin powder, i.e., granular paraffin powder, yielding paraffin powder (granules) with a D50 of 10-1000 μm. During the contact between the paraffin droplets and the cooling gas, the cooling gas, within a preset temperature range, is continuously introduced into the tower to maintain contact with the paraffin droplets, keeping the temperature inside the tower below 30°C. The preset temperature range is below 25°C.

[0035] Step 2: The set amount of paraffin powder used as a molding agent is mixed with the raw materials prepared according to the component ratio and then subjected to dry premixing for a preset mixing time. The set amount is set according to the actual process requirements. The raw materials are added to a mixing device such as a double cone mixer, a Z-type mixer, or a double spiral mixer for dry premixing. The cylinder rotation speed of the dry premixing device is 5-200 rpm, the stirring shaft speed is 5-300 rpm, and the preset mixing time is 0.2-24h. The specific preset mixing time is set according to the requirements during actual operation.

[0036] During dry premixing, the temperature of the inner cavity of the mixing device is controlled to maintain the inner cavity temperature within the range of -30℃ to 50℃. The temperature is controlled by introducing a cooling medium into the inner cavity of the jacket layer of the mixing device cylinder, or by allowing the surface of the cylinder of the mixed substance to directly contact the cooling medium for temperature control. The temperature of the cooling medium is in the range of less than 25℃. The cooling medium can be a cooling gas or a cooling liquid, such as cold air or cold water.

[0037] Step 3: Add the mixture of paraffin powder and raw materials evenly to the ball mill. The ball mill is an existing device, and its specific structure will not be described here. Add the alcohol according to the preset requirements. The preset requirement is that the alcohol density is less than or equal to 0.82 g / cm³. Perform ball milling according to the grinding conditions. The grinding conditions are based on total quantity control, and the solid-liquid mass ratio in the ball milling process is set between 85:15 and 75:25.

[0038] During ball milling, the internal temperature is controlled by introducing a cooling medium into the jacket cavity of the ball mill. The temperature of the cooling medium, such as water or cooling gas, is kept below 25°C. Temperature probes installed on the end caps of the ball mill monitor the internal temperature in real time, aiming to keep it below a preset value, which can be set to 20°C. The internal temperature is checked to see if it reaches 90% of the preset value. When the internal temperature reaches 90% of the preset value, such as 18°C, the amount of cooling medium introduced into the jacket cavity is controlled, such as by increasing the injection rate or initiating the injection process.

[0039] This embodiment uses alcohol as the ball milling medium, which is less harmful to the human body upon direct contact. The equipment safety requirements are lower than with hexane, and alcohol has good wettability with tungsten carbide, improving the suspension of the raw material powder and significantly increasing grinding efficiency. Paraffin wax, used as a forming agent, has a low melting point of approximately 52°C and can solidify instantly below 35°C. This method easily transforms paraffin wax from a solid mass into a liquid state, and then, after atomization, it solidifies instantly upon contact with gas below 25°C, forming paraffin wax particles. Furthermore, using paraffin wax as a forming agent allows for complete vaporization below 550°C during sintering, preventing significant fluctuations in the carbon content of the alloy product. Paraffin wax, as a forming agent, can be recovered during sintering, causing no environmental pollution.

[0040] By using a cooling medium, the temperature during mixing and ball milling is effectively controlled, preventing the paraffin powder (particles) from liquefying and causing segregation, and also preventing the material from oxidizing.

[0041] Compared to existing methods, this embodiment uses atomization to prepare paraffin particles. Paraffin particles are atomized under specific spray pressure or atomizer speed conditions, resulting in finer, more spherical, and more uniform paraffin powder particles. This method prevents paraffin agglomeration and large particles, and ensures uniform dispersion throughout the raw materials during mixing. Furthermore, before ball milling, the paraffin powder and raw materials are pre-mixed using a dry pre-mixing process. This allows for uniform mixing of the paraffin powder (particles) and raw materials in the early stages of ball milling, resulting in better uniformity compared to existing methods that directly add materials into the ball mill. The process involves atomizing paraffin blocks, cooling and solidifying them to form paraffin powder particles, then dry premixing the paraffin powder with raw materials at a certain operating speed, shaft stirring speed, and duration. Finally, alcohol of a certain density is injected during ball milling to control the solid-liquid mass ratio. The overall process is simple, and the multiple process settings and operation controls ensure that the ball-milled metal products do not have holes or large dimensional fluctuations, thus improving the quality of the ball-milled metal products.

[0042] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A process for the preparation of an alcohol-stone wax mixture, characterized in that, The application relates to a method for preparing a circular wax powder, which comprises the following steps: Step 1: melt the paraffin into a liquid, atomize the paraffin into small paraffin droplets, let the small paraffin droplets contact with cooling gas in a tower, continuously input the cooling gas with a preset temperature range (less than 25 DEG C) to contact with the small paraffin droplets, keep the temperature in the tower less than 30 DEG C, and rapidly cool the paraffin into a circular paraffin powder; Step 2: dry premix a certain amount of paraffin powder used as a forming agent with raw materials prepared according to a component proportioning ratio for a preset mixing time, control the temperature of the inner cavity of a mixing device, and keep the temperature of the inner cavity in a range of -30 DEG C to 50 DEG C; Step 3: add the mixture of the paraffin powder and the raw materials into a ball mill, add a preset required alcohol, ball mill according to grinding conditions, control the temperature in the mixing and ball milling process by inputting a cooling medium into the jacket cavity of the ball mill to control the temperature in the cavity, and avoid liquefaction of the paraffin powder and oxidation of the materials, wherein the temperature of the cooling medium is in a range of less than 25 DEG C.

2. A process for the preparation of an alcohol-stearin mixture according to claim 1, characterized in that: In step 1, the paraffin liquid is atomized by using a spraying device based on open or closed principles in a centrifugal or pressure mode, wherein the pressure of the pressure spraying is 100-2000 kPa, and the rotating speed of the centrifugal atomizer is 1000-15000 rpm.

3. A process for the preparation of an alcohol-paraffin mixture as claimed in claim 1, wherein: In step 2, the raw materials are added into a mixing device of a double-cone mixer, a Z-shaped mixer or a double-helix mixer to perform dry premixing, the rotating speed of the cylinder of the dry premixing mixing device is 5-200 rpm, the rotating speed of the stirring shaft is 5-300 rpm, and the preset mixing time is 0.2-24 h.

4. The process for preparing an alcohol-paraffin mixture as claimed in claim 1, wherein: In step 2, the inner cavity of the jacket layer of the cylinder of the mixing device is inputted with a cooling medium to control the temperature, or the surface of the cylinder of the mixing device directly contacts with the cooling medium to control the temperature.

5. The process for preparing an alcohol-stearin blend as claimed in claim 1, wherein: In step 3, the internal temperature is monitored in real time by arranging a temperature probe on the end cover of the ball mill to control the internal temperature to be less than a preset value, the internal temperature whether reaching 90% of the preset value is judged, and when the internal temperature reaches 90% of the preset value, the amount of the cooling medium inputted into the jacket cavity of the ball mill is controlled.

6. The process for preparing an alcohol-stearin blend as claimed in claim 1, wherein: In step 3, the preset requirement is that the density of the alcohol is less than or equal to 0.82 g / cm3, and the grinding condition is that the solid-liquid mass ratio in the ball milling process is set to be between 85:15 and 75:25 based on the total amount control.

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