Overview of Cotton Processing Ginning Process
my country’s cotton finishing plants generally have ginning and velvet stripping processes, some plants also have oil extraction equipment, and a small number of plants have introduced feed protein production processes and equipment. Therefore, my country’s cotton finishing industry covers primary cotton finishing and deep finishing of cotton by-products.
This book only discusses the ginning and velvet stripping process, covering the main contents of blowing, ginning, lint cleaning, cleaning, recycling and packaging of ginning scraps.
(1) Blowing
Blowing is the pretreatment of cotton. The impurity content and moisture content of cotton picked manually or mechanically vary greatly and do not meet the requirements of ginning. Impurities must be cleaned and moisture dried. Otherwise, it will reduce the lint quality and cause mechanical failure.
Impurity cleaning is to remove impurities in cotton. There are many ways and machines to remove impurities from cotton. Different types of cleaning machines should be used for different types of impurities. Centrifugal or automatic sedimentation cleaners should be used for major impurities, and impact or throw-type cleaners should be used for small impurities.
Moisture drying is a process in which cotton with excess moisture evaporates moisture using heat sources under the action of mechanical force. Complementing this is the natural spreading of cotton.
The greater the proportion of machine-picked cotton, the more important the cotton pretreatment becomes.
(2) Ginning
The process of using mechanical action to separate the long fibers and cotton seeds on the cotton is called ginning. After rolling with top rollers, lint and cotton seeds are obtained.
In addition to lint and cotton seeds, after saw-tooth gin rolling, we also get small flower heads, sterile debris and dust. The sawtooth gin has higher requirements for sub-cotton pretreatment than the top roller gin. The higher the output of the sawtooth gin, the higher the requirements for cotton pretreatment.
(3) Lint cleaning
After ginning, lint contains more impurities, short fibers, rags, seeds and other debris, especially machine-picked cotton. The above substances can be removed through mechanical action, but some cotton fibers will also be damaged during the cleaning process.
(4) Cotton seed cleaning
The cleaning work of removing various debris from cotton seeds before stripping and sending them for oil extraction is called cotton seed cleaning. The cotton seeds discharged from the ginning process sometimes contain impurities such as stiff petals and small flower heads, and sometimes contain lint, dust and some unusual impurities, such as screws, nuts and other iron impurities and other hard impurities. Stiff petals and small flower heads entering the velvet stripping process will increase the clothing loss, dust, etc. will affect the impurity content of short velvet. Hard debris will damage the parts of the velvet stripping machine, such as saw blades, etc., and will also emit sparks. In severe cases, it will cause fire. The cotton after stripping will also contain dust and debris, which will affect the oil extraction process. Therefore, ginners must clean cotton seeds before and after the velvet stripping process to improve the quality of linters and cottonseed oil.
(5) Stripping
The process of using mechanical action to separate the short fibers and cotton on the cotton seeds is called stripping. The length and maturity of short fibers on wool cotton seeds are also divided into several levels. Short linters of different lengths and different maturity have different uses. Therefore, the ginner must strip the wool cotton seeds in separate lanes. The long fibers of more than 13mm from the newly stripped wool are called first-line fibers, which can be used to spin thick yarn and make high-grade paper.
The short fibers with a length of 3 to 13 mm are called second-line fleece, which mainly produces nitrochemical fiber. The short fibers stripped off are called sandaorong, which mainly produces chemical fibers or rayon.
(6) Linter cleaning
During the stripping process, due to various reasons, the impurity content or ash content of cotton linters and their properties often vary greatly. To a certain extent, they affect the quality and use value of cotton linters. Therefore, it is necessary to set up a cotton linters cleaning machine in the post-lint stripping process to clean the cotton linters and change their intrinsic quality and appearance.
(7) Packing
Packing is the work of compressing and packaging various fibrous products in the ginning factory. Cotton fiber is a loose material with many grades and is easily contaminated. Therefore, after the ginning or stripping process, a packaging process must be set up to compress the lint or lint into bags in a timely manner to facilitate stacking, storage, transportation and storage, and to avoid mixing different levels of fibers with each other.
(8) Cleaning and recycling of ginning scraps
Ginning scraps generally include small flower heads, infertile debris, car belly velvet, dust tower ash and other debris. After cleaning and classification, these substances are all useful. Lint can be obtained by rolling the small flower heads after cleaning, lint and lint can be obtained by cleaning the infertile lint, lint can be obtained by cleaning the belly lint, lint can be obtained by cleaning the dust tower ash, and the dust after cleaning can also be obtained. It can be used as fuel or raw material for cultivating edible fungi. This shows that there is no waste in the ginning mill.
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