www.cotimes.org   HOME PAGE        Our objective        Our approach        Our commitment   COMPANY        Our charter        Our experience        The founder   RESOURCES       The human resource       The partners       The network   CONTACTS   LINKS       Around the cotton       Organizations       Countries       Misc. Site powered by: 57863 cotimes.org cotimes.org Language: The expertise The consulting Other activities The techniques The questions The events   TECHNICAL ELEMENTS IN THE FIELDS OF COMPETENCE OF COTIMES Cotton ginning: a technology which must be well managed Ginning must be operated according to the cultivated species, the farming techniques, the climate and the fiber markets. Rational practices combined with quite selected equipment make it possible to combine profits, high rates and quality preservation. The cost of ginning represents a significant part of the fiber cost. Limitation of the ginning cost requires a maximum feeding of the process, a good technological level of well-sized equipment, a close maintenance and skilled and trained personnel. The role of the ginner in the development of quality is considerable. The ginning process must be adapted to the primary matter (the seed cotton) and to the target markets. The process must be operated according to the characteristics of the seed cotton and of the actual environmental conditions. This cannot be obtained without a trained and qualified team, able to get the best from the technological innovations, ensuring a perfect maintenance of a flexible process. There is not good ginning nor good quality of the products, without a controlled storage of the seed cotton. The moisture of the seed cotton is the principal factor of storage. During ginning, 60 % of energy is used for the matters transportation and for pollution reduction. Pneumatic transport is prevalent. Expensive in energy, it must be of a maximum efficiency and requires a perfect maintenance. Optimal management and the improvement of the competitiveness of the gin are obtained through the formalization and the modeling of all the practices of management, ginning, storage, maintenance, quality and traceability of the products, accountancy and financial management. That is why COTIMES AFRIQUE developed Gin Win Manager, the unique integrated management software for gin plants. The unloading systems The unloading system feeds the plant with a constant and controlled seed cotton flow. It ensures a pre cleaning and a pre opening of the seed cotton. Pre cleaning at the time of unloading makes it possible to withdraw the heavy objects brought by harvest, before their entry in the regulation hopper. The objective of an automatic feed control is to provide to the process a regular flow of dispersed seed cotton, to allow optimal downstream operations. The unloading system must be adapted to the seed cotton containers and sized according to the seed cotton characteristics and to the plant capacity. The respect of the standards air velocity is important, as well as the pipes sealing. It must be designed to minimize the lengths of pipes and the number of elbows. The feed regulation is fundamental for the performances of the process, while the pre cleaning action protects the material downstream. Management of the cotton moisture Cotton is a hygroscopic matter, which permanently exchanges water with the ambient air to reach hygroscopic balance. The moisture content of cotton arriving at the gin depends on the atmospheric conditions, the mode of harvest and storage. It must be measured and controlled. The hygroscopic property of cotton makes it possible to change fiber moisture during the process. One can dry the seed cotton to reduce and homogenize the fiber moisture content to avoid the chokes and to facilitate opening and cleaning of the seed cotton. An over drying reduce the fiber strength, the commercial length, and yellows the fiber. One can humidify the seed cotton to restore moisture to the fiber, to let it better support the mechanical constraints and aggression in the gin and cleaners, and to avoid the static electricity resulting in chokes. One can humidify fiber before pressing it in bales, to decrease the compression force, to save energy and press, and to increase the bale weight and the ginning outturn. Seed cotton cleaning During the harvest, many foreign matters are picked with the cotton. Cleaning the seed cotton as a first step, removes the foreign matters before entering in the gin stand. The goal is to improve the commercial value of fiber, to open and homogenize the matter. The seed cotton cleaner first opens the seed cotton. Cleaning then is obtained by scrubbing action. The seed cotton extractor withdraws large waste. It is more adapted for cotton mechanically harvested. The extractor must receive opened seed cotton. The gin feeder does an additional cleaning and an opening before the seed cotton enters into the gin stand. It feeds the gin stand uniformly and with a controlled rate. The seed cotton cleaning must be adapted to the seed cotton foreign matter type and content. The cleaning sequence must vary in particular according to the type of harvest. Seed cotton cleaning is very important for good ginning profit, as it removes trashes with much less damage to the fiber, than the lint cleaning itself. Cost of the equipment and effect on the fiber quality require a conscientious maintenance and adjustments in conformity with the recommendations of the manufacturer. The gin stand The gin stand separates the fiber from the seed. It is the heart of the process, which impose the capacity. Gin stand has a very strong impact on the products quality. The saw gin stand includes some systems for an additional cleaning of seed cotton and fiber. The roller gin stand is of lower capacity, and does not include cleaning devices. The gin stands with high capacity used according to recommendations of the manufacturer do not generate more breakages of fiber or damage with seed, compared to the older machines. Beyond these recommendations, the effect relates to the length, the neps and damages to the seeds. The influence of gin stand on the rate and cost of ginning as on the quality itself, requires a scrupulous maintenance in terms of monitoring and replacements of wearing parts in contact with the matter, like in terms of adjustments. The lint cleaning Coming out of gin stand, fiber includes foreign matters and presents a more or less irregular and matched aspect. Grade has a strong commercial importance. So the fiber must be cleaned and combed. The lint cleaning improves its commercial value by improving the grade. The centrifugal type lint cleaner is right behind the gin stand. Centrifugal cleaners gently eliminate coarse or dense waste. It does not damage fiber, but cleans only slightly and does not correct the aspect, because it does not open the fiber mass. The saw lint cleaner individualizes fibers and foreign matters are eliminated by opening, scrubbing action, centrifugation, gravity. Cleaning is much more effective and the fiber is homogenized thanks to the combing action. The fiber suffers damage however (length reduction, short fibers, neps). A perfection in the adjustments, as well as a good control of the parameters of operation like feed rate and combing ratio are fundamental to ensure a maximum effectiveness with minimal fiber damages or losses. The manufacturers recently released devices allowing to optimize the fiber cleaning cost-benefit by adjusting cleaning and fiber losses. The lint conditioning The objective of the lint conditioning is to compress and protect the fiber for its storage and handling. The press receives a bat of lint from the condenser and the pusher. After a pre-compression by a tramper, the hydraulic press ensures the pressing of the bale. Bales are wrapped with steel wires, and fabrics or bags of plastic, jute, or cotton. The maintenance The good performances of a ginning unit depend on the equipment, but also on the competence of the personnel, the regularity of maintenance, the respect of the adjustments and of the rates recommended by the manufacturer. The non-observance of these principles rapidly causes rates of production and quality of the products to fall, with an increase in the costs and damage to the equipment. A program of maintenance well conceived is not limited to the maintenance of the equipment. It also has an effect on safety, quality, on the costs of energy and repair, and finally on profitability. The management must take in hand the program of maintenance and imply the employees. The annual revision aims to carry out repairs in a scheduled and meticulous way, to avoid incidents and breakdowns during the ginning season. The preventive maintenance aims to reduce the costs of repair and to increase the production rate by a regular and programmed maintenance, before the serious problems arise. The staff training A qualified personnel can acquire, assimilate and use information. A trained and informed personnel can make the good decisions. To allow the best industrial performances, the personnel must benefit of a regular training, in particular concerning operation of the equipment, maintenance, adjustments and safety. The training can be carried out on site by qualified technicians. The benefit is immediate and the cost is low. A complementary training can be done out of the site through specialized seminars, or through specialized courses of ginning schools. The delinting of cotton seed The mechanical delinting is used to mechanically remove the fibers remaining on the seed coat after ginning, called “linters”. The seed after being cleaned (extraction of the foreign matters) is treated by circular saws for a progressive detachment of linters. It is a violent and repetitive action, which can damage a part of the seeds. Mechanical delinting cannot be used for planting seeds. After being delinted, the seed is directed towards the following stages (decorticators, beaters, etc), whereas the linter is baled directly or after being cleaned, for many different uses. The chemical delinting with the sulphuric acid, reserved for planting seeds proceeds by hydrolysis of the linter. Delinted seeds are sorted to separate those having the best germination performance (highest density), and then treated with chemicals and finally put in bags. The process using diluted sulphuric acid The process was developed in the USA at the beginning of the Seventies by Cotton Incorporated to fit the requirements of cost, environmental protection and preservation of the intrinsic qualities of the planting seed. The raw seeds are put in contact with a sulphuric acid solution. The wet seeds are introduced into a dryer, where a hot air stream evaporates water and concentrates the acid. The linter is hydrolysed. The delinted seed is then cleaned and sorted by gravimetric table. Good seeds are forwarded to the treater where chemicals, neutralizer and dye are applied in coating. The engineering and the control of a chemical delinting process must take into account the men and environment harmfulness of the inputs used. A very powerful and efficient system is absolutely necessary to collect dust and effluents containing acid and chemicals. Because of its energy and infrastructures cost, such a system is too often neglected. The chemical delinting helps to develop of the cotton sectors Increase of seed cotton yield thanks to: - A better germination ability, - A faster imbibition of seed, - Better sanitary conditions, - The mechanization of sowing, - A less thinning stress. In favourable soil water conditions at the germination, chemically delinted and treated seeds can offer a 10 to 15 % yield increase on average. This should not hide an important variability because of heterogeneity of the pédo-agro-climatic factors in the cotton growing areas. Increase of the products quality All that allows a good start of plant growth and keep the plant in good sanitary conditions is in favour of the fiber and seed quality. All the effects of using cotton seed, as enumerated above, represent an important source of quality improvement. Generation of economies The seed delinting makes it possible to reduce the weight of seeds used to plant an hectare. The seeds thus saved (up to 25 kg of seeds per hectare in Africa) can be used for oil and animal food production, which constitute an additional income for the industrialist. The very important reduction in seeds weight (up to 75 %) to be transported, handled and stored is very significant. The reduction in pesticides used for seed treatment is high, by the cumulated effects of less seed weight to be treated and less chemical consumption per kg of seed of delinted seed. Indirect effects of the chemical delinting (the case of French-speaking Africa) - Motivation of the growers, - Better seed multiplication programs, - Preservation of the genetic purity, - Support and training of the farmers. Sowing delinted seed cannot be practised when the soil is dry. The delinted seed releasing must then be done along with extension actions toward the growers, just like any new cultivation practice. It is however a question of modifying in a very light way the practices of sowing, which does not requires a high level of technical skills, and can thus be obtained easily. Economic effects of using delinted seeds The cost of delinting represents a few hundreds of FCFA per kg of seeds. - For the grower, an additional income. The impact on the rural economy is positive. - For the ginner, an additional income by increase in fiber and seed production and in those products quality. - For the State, a help in improving the rural economy, and a taxes income increase. Cotton plant products quality The spinning mill is the principal outlet of cotton fiber produced in the world (more than 90 %). The spinners objectives are the improvement of the products quality and the reduction in production costs. The quality of products strongly depends on fiber quality. The cost of fiber represents according to cases' 40 to 60 % of the yarn cost. These constraints added to the technical evolution of the spinning and weaving processes bring the spinners to much rigour in the choice of raw material. He needs the fiber matching his product’s quality requirement and allowing the best operation of textile machinery, at the lowest price. Although being a secondary product, the seed must also fit quality requirements to be processed and paid. The Cotimes experience extending from the plant to the textile industry offers a unique approach the products quality as a whole. The quality strategies and the quality charters Quality is an essential factor of profitability of the cotton sectors. Its importance keeps increasing because of the increasing requirements of the users, competition on the market and because of the increasingly precise and complete description of the products (HVI classification of fiber). For the cotton producers, to work out strategies of quality becomes essential. The concept of quality is based initially on the intrinsic characteristics of the matter, but must also include the lots homogeneity and the respect of the commercial contracts. The improvement of quality for a maximum valuation of the productions can be conceived only through one overall step, integrating all the phases and implying the whole of the actors, from the field to the port. The principle of quality charters consists with pushing the actors toward responsibility. They take engagements in a contract, which defines each one’s role and actions in favour of quality. The impact of industrial practices on products quality The cotton fiber has its maximum quality potential when the boll opens. It undergoes various degradations before and during harvest. Ginning makes it possible to improve certain characteristics, while affecting some others negatively. Cleaning seed cotton and fiber make it possible to eliminate foreign matters, while heat and mechanical treatments will damage the fiber. Ginning definitely has a huge potential effect on productions quality. The generalization of automated classification instruments (HVI) means a greater visibility of the effect of ginning on quality parameters. Ginning will have to be managed and adjusted with a strong focus on quality. Ginners thus have a very important responsibility on quality of the cotton productions. Quality parameters as affected by ginning Ginning, by the strong mechanical constraints imposed on fiber, involves breakages, decreasing the commercial length and uniformity, and increasing the short fiber content. Ginning can reduce strength. The ginning process reduces the vegetal and mineral contaminants, but can generate organic contaminants (oils, grease). The composition of ginning process (in particular the seed cotton and fiber cleaning) must be adapted to the types of contaminants met in the zone of production, and according to the market requirements. The seed coat neps (seed-coat-fragments) are generated mainly at the gin stand, in particular under conditions of low moisture seed. A proportion of the neps will be eliminated at the carding stage. The neps affect spinning mill operation and final products aspect. Ginning management toward products quality control The ginning process must be adapted to the local producing conditions, which determine the characteristics of the primary matter (seed cotton and fiber), and to the fiber market. Thus the climate, the cultivation methods, the cultivated species and variety, are major elements of decision for the design of a ginning process. The use of selected equipment must be reasoned according to the characteristics of the seed cotton (moisture, trash) and according to the environmental conditions. This is why the ginner must be trained and to operate adapted equipment. The technological development of cotton fiber classification During the last A.C.A. meeting in Dakar, the quality has been strongly presented as a major element of the African cotton competitiveness. The concept of quality is based initially on the intrinsic characteristics of the matter, but must also include the lots homogeneity and the respect of the commercial contracts. The markets become increasingly technical. The totality of American and Australian cotton is classified using HVI technology, which allows an objective estimation of characteristics of high importance for the spinner. The characteristics of synthetic fibers are very homogeneous and well defined. So the traders are generally equipped with HVI lines. The evolution of Africa toward HVI classification is a key factor of the competitiveness of her cottons. The awaited profits are short-term and longer-term, through: - A better knowledge of the product for better selling it, - The construction of a better image of the producer, - A tool for producing practices improvement. The realization of a HVI classification facility not only consists in purchasing one or more measuring units. It must respect many conditions, which, fault of being respected, will not allow a commercial exploitation. This has unfortunately occurred in certain countries of the continent. Return on investment are impossible if the facilities don’t meet the international standards, providing results of good quality, stable in time. This implies: - A serious study of the context and needs, - A design by specialists, - A reliable and internationally recognized equipment of measurement, - An air conditioning design to meet the international standards, - A study of classification methodology, in order to obtain sufficient precision of results, - A staff training to cotton technology and to the work organization in the laboratory (preparation, preconditioning, analyses, storage...), - A follow-up of the measurements quality on the long term. COTIMES capitalizes an experience recognized in the field of cotton technology, which allows the company, in partnership with the CIRAD, to propose the design and realization of quality control and classification laboratories, that match the above requirements. Ginning by products and waste cleaning and utilization The ginning process generates by-products, which can be used after some treatment. This is the case of the lint-cleaner trash, which contains a significant proportion (up to 70 %) of fibers of variable length, which can be used on the local markets or the international market. A use of waste through cotton bale bags is common in Brazil and seems to develop in Africa. Cotimes holds the expertise as well for such cleaning (average and high capacity) and manufacturing processes. A cotton industry which respects the environment Cotton industry (ginning, delinting or textile industry) generates potentially harmful matters for the environment and the men if they are badly controlled. The ginning process uses a great quantity of air for the transport of seed cotton and fiber. It generates waste and releases dust and fiber fragments. Waste represents important tonnages (up to 30 % of the weight of seed cotton according to the type of harvest). They must be used, recycled, in an economically and ecologically satisfactory way. In chemical delinting, waste and generated dust are acid and can include plant protection chemicals. Their harmfulness is large for the personnel and the environment. Many factories do not have sufficiently powerful dust extraction equipments, which present risks for the personnel and the environment especially in residential area. Mineral and vegetal dusts and chemical effluents are the potential dangers. Cotimes regards the aspects of environmental protection as very important and having to be integrated in any industrial project whatever the country or the operation area. BIBLIOGRAPHY Books Cotton Ginners Handbook, USDA/ARS, Agricultural Handbook " 503, Décembre 1994 ; W.S. Anthony and W.D. Mayfield Managing Editors. Cotton Contamination Survey, International Textile Manufacturers Federation (ITMF); Am Schanzengraben 29 Postfach, CH-8039 Zürich Papers DREAN J.-Y., RENNER M., CHANSELME J.-L., 1997. Que filerez-vous demain ? In : L’Industrie Textile, n°1291, octobre 1997. CHANSELME J.-L., 2001. Ginning Cotton while preserving its quality. Cotton Ginning Breaking Session, ICAC 60th plenary meeting, Victoria Falls, Zimbabwe ; Sept. 16 - 21, 2001. Egrener le coton en préservant sa qualité. CHANSELME J.L., 2002. Le délintage chimique des semences, facteur de développement des cultures cotonnières. Afrique Agriculture, n° 304, juin 2002. CHANSELME J.L., 2003. Egrener le coton en Afrique, en maîtrisant les coûts et en préservant la qualité. Afrique Agriculture, n° 315, juin 2003. BACHELIER B., CHANSELME J.L., 2004. Le laboratoire de caractérisation du coton en Afrique : un outil puissant de valorisation des productions, exigeant en technicité, de la conception à l’utilisation quotidienne. Afrique Agriculture, n° 326, juin 2004. Expert Panel on Commercial Standardization of Instrument Testing of Cotton, 2004. CSITC, Andrew G. Mc Donald, LCA, in Proceedings of 27th International Cotton Conference, Bremen, March 24-27, 2004. Communication présentée par Gérald Estur, statisticien du CCIC, lors de la Réunion Ministérielle de Concertation Régionale sur la filière coton dans la zone UEMOA le 18 juin 2003 à Ouagadougou. http://www.icac.org/icac/cotton_info/speeches/estur/2003/uemoa.pdf Communication présentée par Gérald Estur, statisticien du CCIC, lors du Séminaire technique de l’Association Cotonnière Africaine le 5 mars 2004 à Dakar, Sénégal. http://www.icac.org/icac/cotton_info/speeches/estur/2004/aca_04.pdf The registered office of COTIMES limited liability company is in France in Languedoc Roussillon (Hérault34) more exactly to: Saint Mathieu de Tréviers  F-34270  Chemin de Bassac RC 451 968 713 APE 742 C NII: FR90 451 968 713 CNIL: 1038108 Phone: (33) 4 67 66 75 43  Sites optimisés pour Internet Explorer 6 résolution d'écran de 1024x768 pixels*  Hello you have as addresses IP 38.107.191.80   We are on Monday 6 September 2010 - Les cookies sont acceptés par votre navigateur - L'option java est NON activée Votre hôte DNS : 38.107.191.80