Glass bottle production process

Release time :

2023-02-23

In the previous issue, we introduced the characteristics of glass bottles. Next, introduce the glass bottle production process. Reminder: For those who have not read the previous issue, it is recommended to read the previous issue first, which will be helpful for reading this issue. To understand the glass bottle production process, start with the following two points. 1. Raw material ratio: Usually the raw material formula of glass bottles (soda-lime glass bottles) is mainly quartz sand, soda ash, limestone, sodium nitrate, nickel oxide, and broken glass. Although cullet is added to the formula, it plays an important role in the whole formula. It can reduce raw material cost, reduce processing energy consumption, improve melting rate, facilitate clarification and homogenization, and prolong the service life of the kiln.Although adding cullet has many advantages, there are still some disadvantages. For example, the fluctuation of the composition caused by its volatilization, the impact of refractory material erosion on the quality of the glass, secondary bubbles, easy to bring in impurities, and unsuitable particle size will affect the melting. There are not no solutions to the above drawbacks, and the specific solutions are as follows: (1) Supplement the fluctuation of components caused by volatilization and loss Comparing the full analysis of cullet with the analysis content of the original glass, determine the composition and content that should be supplemented, and then carry out calculation and verification to see if it meets the design composition requirements. In actual production, through the testing of glass density, thermal expansion coefficient softening point and ring shear stress, the change of glass composition can be grasped in time, so that the glass composition can be controlled within the design range. (2) Appropriate ratio of cullet used Generally, manufacturers believe that when the amount of cullet used in melting soda-lime-silica glass exceeds 50%, the quality of the glass will be reduced, and the mechanical strength will become brittle. However, proper supplementation of oxidants, clarifiers, fluxes, and some volatile components (B2O3, Na2O, etc.), and full homogenization of the glass will not affect the color and performance. (3) To ensure the proper lumpiness of cullet When the particle size of broken glass is less than 0.25mm or between 2-20mm, it has a good effect on melting. The latter particle size is used in production to reduce the power used for crushing. Taking into account the processing factors of cullet of various shapes, the particle size of 20-40mm is usually used. (4) Strict management and processing of broken glass The processing of recycled materials in the factory is relatively simple, because the same components fluctuate, and basically can be used directly. However, when the purchased cullet is used, because the quality fluctuates greatly and contains more impurities, it is stored separately from the returned materials of our factory and strictly managed. In addition to cleaning, sorting, impurity removal and magnetic separation to remove iron to package glass quality, samples must be taken frequently for analysis, and the batch materials should be adjusted appropriately according to the chemical composition. 2. Heating process The kiln is made of refractory materials, and the heating method is to spray flames from the upper end. The raw materials fed in from the feeding port are heated to about 1600°C to dissolve them. Due to the action of gravity, the heated glass paste flows from the clarification tank to the shearing pipe. The temperature of the kiln should not be lowered to normal temperature after starting to use, otherwise the refractory material will crack and cannot be used. The general kiln overhaul period is three to five years, and refractory materials need to be laid after overhaul. The whole heating process mainly includes forming process and annealing process. (1) Forming process: The glass paste flows from the clarification tank to the shearing pipe, and the shearing knife cuts the liquid into a set weight and then flows into the mold for molding. Glass bottles are generally divided into two types of molding methods according to the caliber size: blow blowing method and pressure blowing method. (2) Annealing process: After the empty bottle is molded and thermally sprayed, it passes through a cooling channel about 30 meters long, and sprays flames on one side of the cooling channel to maintain the temperature of the bottle body and prevent the empty bottle from being broken due to sudden cooling. During the annealing process, the glass bottle is gradually cooled from 500°C to room temperature, and the entire annealing process takes about 30 minutes.

To understand the glass bottle production process, start with the following two points.

1. Raw material ratio:

Usually the raw material formula of glass bottles (soda-lime glass bottles) is mainly quartz sand, soda ash, limestone, sodium nitrate, nickel oxide, and broken glass. Although cullet is added to the formula, it plays an important role in the whole formula. It can reduce raw material cost, reduce processing energy consumption, improve melting rate, facilitate clarification and homogenization, and prolong the service life of the kiln.Although adding cullet has many advantages, there are still some disadvantages. For example, the fluctuation of the composition caused by its volatilization, the impact of refractory material erosion on the quality of the glass, secondary bubbles, easy to bring in impurities, and unsuitable particle size will affect the melting.

There are not no solutions to the above drawbacks, and the specific solutions are as follows:

(1) Supplement the fluctuation of components caused by volatilization and loss

Comparing the full analysis of cullet with the analysis content of the original glass, determine the composition and content that should be supplemented, and then carry out calculation and verification to see if it meets the design composition requirements. In actual production, through the testing of glass density, thermal expansion coefficient softening point and ring shear stress, the change of glass composition can be grasped in time, so that the glass composition can be controlled within the design range.

(2) Appropriate ratio of cullet used

Generally, manufacturers believe that when the amount of cullet used in melting soda-lime-silica glass exceeds 50%, the quality of the glass will be reduced, and the mechanical strength will become brittle. However, proper supplementation of oxidants, clarifiers, fluxes, and some volatile components (B₂O₃, Na₂O, etc.), and full homogenization of the glass will not affect the color and performance.

(3) To ensure the proper lumpiness of cullet

When the particle size of broken glass is less than 0.25mm or between 2-20mm, it has a good effect on melting. The latter particle size is used in production to reduce the power used for crushing. Taking into account the processing factors of cullet of various shapes, the particle size of 20-40mm is usually used.

(4) Strict management and processing of broken glass

The processing of recycled materials in the factory is relatively simple, because the same components fluctuate, and basically can be used directly. However, when the purchased cullet is used, because the quality fluctuates greatly and contains more impurities, it is stored separately from the returned materials of our factory and strictly managed. In addition to cleaning, sorting, impurity removal and magnetic separation to remove iron to package glass quality, samples must be taken frequently for analysis, and the batch materials should be adjusted appropriately according to the chemical composition.

2. Heating process

The kiln is made of refractory materials, and the heating method is to spray flames from the upper end. The raw materials fed in from the feeding port are heated to about 1600°C to dissolve them. Due to the action of gravity, the heated glass paste flows from the clarification tank to the shearing pipe. The temperature of the kiln should not be lowered to normal temperature after starting to use, otherwise the refractory material will crack and cannot be used. The general kiln overhaul period is three to five years, and refractory materials need to be laid after overhaul. The whole heating process mainly includes forming process and annealing process.

(1) Forming process:

The glass paste flows from the clarification tank to the shearing pipe, and the shearing knife cuts the liquid into a set weight and then flows into the mold for molding. Glass bottles are generally divided into two types of molding methods according to the caliber size: blow blowing method and pressure blowing method.

(2) Annealing process:

After the empty bottle is molded and thermally sprayed, it passes through a cooling channel about 30 meters long, and sprays flames on one side of the cooling channel to maintain the temperature of the bottle body and prevent the empty bottle from being broken due to sudden cooling. During the annealing process, the glass bottle is gradually cooled from 500°C to room temperature, and the entire annealing process takes about 30 minutes.

The production process of glass bottles has been explained to everyone, and the next issue will introduce the surface treatment of glass bottles.We welcome more people to pay attention to our company, ZHUHAI BAOLI FOAM SPRAY PUMP CO.,LTD.

E-mail: Jacky@zhbaoli.com

P.O.BOX: 519085

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Zhuhai City, Guangdong Province, China