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TYPES OF COCOON RAW MATERIAL WASTES AND THEIR APPLICATION IN
THE RECYCLING PROCESS..
Andijan State Technical Institute
Sulaymanov Sharif Abdumanabovich
Abstract:
This scientific paper analyzes the types of silk waste and the standards applied in their
recycling process. Adhering to the standards for waste generated in sorting and silk reeling
sections helps to improve product quality.
Keywords:
los, gumbak, defective, ugly, spotted, soft, hole, unraveled, thin-shelled silk, kaznok,
control skeins, seriplan reels.
ВИДЫ КОКОНОВЫХ ОТХОДОВ И ИХ ИСПОЛЬЗОВАНИЕ В ПРОЦЕССЕ
ПЕРЕРАБОТКИ.
Андижанский государственный технический институт
Sulaymanov Sharif Abdumanabovich
Аннотация:
В данной научной работе анализируются виды шелковых отходов и
стандарты, применяемые в процессе их переработки. Соблюдение стандартов для отходов,
образующихся на этапах сортировки и перекручивания шелка, помогает улучшить
качество продукции.
Ключевые слова:
лос, гумбак, дефектные, уродливые, пятнистые, мягкие, с дырками, не
перекрученные, тонкокожие шелковые отходы, казнок, контрольные мотки, сериплановые
катушки.
The demand for silk fiber in the global market has been increasing significantly year by year.
According to data from the International Silk Association Committee (ISAC), in recent years,
more than 153,000 tons of raw silk have been produced worldwide [1]. On a global scale, special
attention is being paid to the efficient utilization of raw silk, increasing the use of silk waste
fibers as secondary raw materials, improving product quality, expanding product assortments,
reducing production costs, and identifying and eliminating factors that negatively affect product
quality at all stages of initial processing and reprocessing of silk waste fibers. From this
perspective, improving the consumer properties of silk fiber and increasing the competitiveness
of silk products in the global market is considered of great importance.
It is well known that in recent years, our country has ranked fourth in the world in
silkworm cocoon production, following China (650,000 tons), India (280,000 tons), and Vietnam
(50,000 tons), producing over 26,000 tons of silk annually [2]. The process of raising silkworms
and obtaining high-quality cocoons is closely connected to the availability and quality of
mulberry leaves, which serve as the main feed for silkworms [3]. Therefore, in order to ensure
the production of high-quality and abundant silk cocoons in our Republic, a total of 50,193.3
hectares of mulberry plantations have been established. These plantations contain around 80.7
million mulberry saplings (Table 1).
Table 1.
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Area of existing mulberry plantations and the amount of fresh cocoons produced during the 2023
silk season in our Republic
№ Regions
Existing mulberry orchards
Quantity of produced live
silkworms, t
Orchards,
h
Single-row
mulberry
trees, one thousand
pieces
1
Republic
of
Karakalpakstan
2541,0
3283,2
852,6
2
Andijan
4683,1
5397,6
3303,4
3
Bukhara
5222
13582
3099,71
4
Jizzakh
2192
2350
641,5
5
Kashkadarya
7303,1
3923,5
3082,1
6
Navoi
1444,5
2783
1007,9
7
Namangan
3048,2
6177,7
2727,2
8
Samarkand
8262
10413,5
2829,75
9
Surkhandarya
3434,2
7617,4
1552,7
10 Syrdarya
1551,5
1591,1
616,0
11 Tashkent
3053,7
5719,9
1641,44
12 Fergana
3297
13354,4
2714,94
13 Khorezm
4158
4540,5
2178,36
Total
50193,3
80733,8
26347,6
In our country, there are currently 28 silk-reeling enterprises for full processing of
26,347.6 tons of raw silk produced. In these silk-reeling enterprises, a total of 2,139 tons of raw
silk is being processed, mainly in yarns with densities of 2.33 and 3.23 tex.
The existing silk-reeling enterprises in our country are mainly equipped with 80 series of
automatic silk-reeling machines and 10 series of mechanical silk-reeling devices manufactured in
China (FEIYU-2000 EX, FY-2000 EX, FY-2008, and KMS), South Korea (KSS-RS-100, KMS),
Japan (NISSAN), and Uzbekistan (KSM-10, KS-10). The total number of hooks amounts to
32,550 (Table 2) [4].
Table 2.
Silk production enterprises in Uzbekistan
№
Name
of
the
enterprise
Installed
device
or
machine brand (country
of manufacture and
year)
Installed series and
number of hooks
Type and quantity
of products being
produced
number
of
series
number of
hooks
Raw silk,
tex
tons
Republic of Karakalpakstan
1
“Asian Silk”
LLC (Vietnam)
FEIYU
2000
EX
(China 2010 y.)
2
800
2,33 and
3,23
50
Andijan region
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2
“Harir Tola” OJSC FEIYU
2000
EX
(China 2010 y.)
1
400
2,33 and
3,23
25
3
“Royal Silk” OJSC КСС- RS-100
(South Korea, 2000 y.) 4
1600
2,33 and
3,23
100
4
“Sapfir Sanoat”
NISSAN
(Japan 1982 y.)
3
90
Row silk 15
5
“Andijan
Xonoy
Silk” OJSC
FEIYU
2000
EX
(China 2010 y.)
2
800
2,33 and
3,23
50
Bukhara region
6
“Bukhara Brilliant
Silk” QK
FY- 2008
(China 2010 y.)
8
3200
2,33 and
3,23
150
7
“Romstar”
QK
FEIYU
2000
EX
(China 2010 y.)
4
1600
2,33 and
3,23
80
KMS- 10 (Uzbekistan
1986 y.)
2
240
2,33 and
3,23
20
8
“Silk
Service”
OJSC
KS- 10
(Uzbekistan
2004 y.)
2
300
2,33 and
3,23
56
9
“Qumushkent
Silk” OJSC
KMS (South Korea
2012 y.)
2
300
2,33 and
3,23
50
Jizzakh region
10 “Bunsan Silk” QK FEIYU
2000
EX
(China 2010 y.)
3
1200
2,33 and
3,23
75
Kashkadarya region
11 “Radian Silk” QK
FEIYU
2000
EX
(China 2013 y.)
4
1600
2,33 and
3,23
120
Navoiy region
12 “Richard
Best
Silk” OJSC
FEIYU
2000
EX
(China 2012 y.)
2
800
2,33 and
3,23
50
13 “Xatirchi
Pilla
Xazinasi” XK
FEIYU
2000
EX
(China 2012 y.)
1
400
2,33 and
3,23
25
Namangan region
14 “Golden
Silk”
LLC
FEIYU
2000
EX
(China 2009 y.)
4
1600
2,33 and
3,23
100
15 “Marjona
Fayz-
Fiber” OJSC
FY 2000 EX
(China 2007 y.)
2
800
2,33 and
3,23
50
16 “Veregrov
Silk”
OJSC
FY 2008
(China 2013 y.)
3
1200
2,33 and
3,23
100
17 “Oydinkul Trade
Service” XK
KMS- 10 (Uzbekistan
1990 y.)
1
100
Row silk 7
KS- 10
(Uzbekistan
1992 y.)
1
160
Row silk 12
Samarkand region
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18 “Jiloi Malika” XK KMS
(China 2012 y.)
1
400
Row silk 25
19 “Kumush
Fiber”
XK
FEIYU
2000
EX
(China 2012 y.)
1
400
2,33 and
3,23
25
20 “Elbek TRJ”
FEIYU
2000
EX
(China 2013 y.)
1
400
2,33 and
3,23
25
Tashkent city
21 “Great
Turan
Gold” OJSC
FY- 2000
(China 2004 y.)
5
2000
2,33 and
3,23
150
22 “Silver Silk” QK
FEIYU
2000
EX
(China
2006- 2007 y.)
11
4400
2,33 and
3,23
275
Tashkent region
23 “Ravnaq Silk” QK FEIYU 2000
(China 2007 y.)
2
800
2,33 and
3,23
50
24 “Singapoor-
Samarkand” QK
FEIYU
2000
EX
(China
2007- 2008 y.)
10
4000
2,33 and
3,23
250
Fergana region
25 “Nurli Tong Silk”
OJSC
FEIYU
2000
EX
(China 2011 y.)
2
800
2,33 and
3,23
65
26 “Vodiy Mirjoni”
XF
KMS- 10 (Uzbekistan
2001 y.)
1
160
Row silk 14
Surkhandarya region
27 “Inter Silk Pro”
QK
FEIYU
2000
EX
(China 2012 y.)
2
800
2,33 and
3,23
50
Khorezm region
28 “Khorezm Fiber”
OJSC
FY- 2000
(China 2008 y.)
3
1200
2,33 and
3,23
75
Analysis of the data presented in the above tables shows that, on average, more than 10–12 kg of
fresh cocoons are consumed to produce 1 kg of raw silk in our country. In particular, in 2022–
2023, the dry cocoon yield coefficient from fresh cocoons was 2.87 kg, which is higher than the
standard agrotechnical norm of 2.72 kg. On average, 1,000–1,100 tons of silk fiber waste of 11
types are generated annually in silk-reeling enterprises (Table 3). Of these, 7 types are suitable
for spinning into silk yarn, cotton-silk, and wool-silk blended yarns due to their physical-
chemical and physical-mechanical properties [5]. The remaining 4 types are not suitable for
producing silk or blended yarns using the current production technologies, but are widely used in
the production of artificial and synthetic fibers, nonwoven materials and fabrics, silk wadding,
paper, surfactants, thermal insulation materials, and other nanotechnology products [6].
Currently, even in countries with a well-developed silk industry, great attention is paid to
the production of valuable goods from silk fiber waste, primarily yarn made of pure silk or a
mixture of natural and synthetic fibers. These waste fibers are efficiently used as low-cost natural
resources to produce various high-value products. Silk fiber waste is also used to make filters for
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purifying water from motor and vegetable oils, films for biomedical and other applications,
membranes for imparting the properties of natural silk to carbon fibers, and other similar
products (Table 3).
Table 3.
Some characteristics of silk fiber waste
Type of silk fiber waste
Descriptions and specific properties
Linear
density
(mg/tex)
Breaking
strength
(cN)
Elongation at
break (%)
Sericin
content (%)
Cocoon floss
375-385
6-7
13-14
35-38
String
360-376
7-9
13-15
25-27
Tangled silk
355-370
7-9
14-16
25-27
Silk fragments
233-323
7-9
16-18
20-22
Reeling scraps
233-323
7-9
16-18
20-22
Test bobbins
233-323
7-9
16-18
20-22
1st-grade waste
265-302
5-6
11-13
18-20
Fiber cut from rollers
302-342
7-9
13-15
25-27
Seed cocoons
250-380
6-7
12-15
25-30
Double cocoons
260-400
6-7
13-15
25-30
Unreelable cocoons
232-305
5-6
11-14
25-27
Analysis of the data in Table 3 shows that the characteristics and properties of silk fiber waste
are quite similar. Therefore, they can be processed under the same conditions. However, it is
necessary to improve the initial treatment technologies and prepare the fibers for spinning.
Because for spinning yarn from silk fiber waste, the material must meet technological
requirements, especially regarding the residual sericin, oils, waxy substances, and soap content.
However, the incoming raw materials (waste) to spinning enterprises often have significantly
higher sericin and oil content. Annually, more than 1,000–1,100 tons of 11 types of silk fiber
waste are generated in silk-reeling enterprises (Table 3). Of these, 7 types are suitable for
spinning due to their physical-chemical and mechanical properties [9]. The remaining 4 types are
not compatible with current production equipment and are thus used for manufacturing artificial
and synthetic fibers, nonwoven fabrics, silk wadding, paper, surfactants, insulation materials, and
other nanotech products [10].
In the sericulture sector and silk-reeling enterprises, a large volume of defective cocoons and silk
fiber waste is generated. These waste materials are highly valuable in the national economy
because, for every kilogram of raw silk produced, about one kilogram of various waste is also
generated. Defective cocoons and silk waste are considered valuable raw materials in spun silk
production. Meanwhile, pupae are used as feed for animals and fish, as they contain about 50%
protein and 27% fat.
Silk-reeling waste is categorized by its origin: from sorting sections, reeling sections, and quality
control units. Waste from the sorting section includes cotton-like floss, defective cocoons, highly
stained cocoons, large-sized or smooth-surfaced cocoons, and those with deformities such as
hollow, thin-shelled, or double cocoons. Waste from the reeling section includes cocoon floss,
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reeling residues, unreelable cocoons, silk fragments, and pupae. The quality control unit
produces waste such as silk fragments, sample bobbins, and seriplan packages.
Main part. Reprocessing the waste generated in sorting sections requires adherence to several
standards. Cotton-like floss accounts for 0.3–0.5% of the dry cocoon mass and contains various
impurities, including up to 40% sericin. After processing, it is divided into two grades and
pressed into bales. The first grade includes clean, uniform-colored floss with no more than 1%
impurities. The second grade includes manually or mechanically cleaned floss with mixed colors
and up to 3% plant impurities. Sorted floss is pressed into bales not exceeding 40 kg. The yield
of defective and double cocoons varies (subject to change) depending on sorting practices.
Name
Value
Double cocoons
1-2
Deformed shape
0,2-0,4
Soft cocoons
1,5-3,0
Spotted (surface spots)
1-2
Internal spots
0,5-1,0
Partially reeled
0,5-1,0
Thin-shelled
0,3-0,6
Pierced
0,1-0,2
Other defective cocoons
0,9-1,8
Total:
6-12
In the cocoon reeling workshop, the cocoon waste (reeling waste) may contain no more than 1%
of unusable cocoons, tangled cocoons, and double cocoons in relation to the total waste mass,
and no more than 0.5% of condensed knots. The average mass of the initial section of the thread
extracted from the cocoon waste must not exceed 1.1 g.
The cocoon waste from automatic reeling appears in two forms:
• Waste wound around the RK machine wheel. This type is cut off every 1.5–2 hours during
operation, straightened, tied together with a thread, and collected into bundles. This waste may
contain up to 2% of unusable cocoons, unreelable cocoons, and double cocoons in relation to the
waste mass.
• Knot-shaped waste. This is manually loosened and sent to the waste processing section. It may
contain up to 2% of unusable cocoons and double cocoons. The moisture content of cocoon
waste is around 200%.
In the waste processing section, cocoon waste is washed and squeezed in a centrifuge,
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cleaned from foreign impurities, dried, sorted by color, and packed into bales. Double cocoons
are categorized as either normal (round or oval) or deformed. The normal type is preferable for
reeling silk with a linear density of 5 deniers or more, while the deformed type is more suitable
for spun silk production.
Conclusion.
Processing waste in the cocoon industry not only brings economic benefits but also
holds great ecological importance. Through recycling, valuable products can be derived from
waste, thus reducing environmental pollution. Each type of waste has specific processing
requirements. For example, cotton-like waste must go through special cleaning processes to
reduce impurities. This type contains sericin, and it can be divided into two grades: the first
grade with fewer impurities, and the second grade with more plant-based contaminants.
Defective cocoons include double cocoons, deformed, pierced, thin-shelled, or spotted cocoons.
Each requires individual cleaning and sorting procedures. Double cocoons, when unusable for
reeling, may be processed into feed for animals and fish due to their high protein and fat content.
For this purpose, proper feed standards must be followed. In conclusion, adhering to standard
requirements for waste recycling in cocoon production enterprises ensures efficient utilization of
materials. Proper processing of waste from sorting and reeling departments increases production
efficiency and enables the creation of useful products. Understanding the composition of cocoon
waste and the specific processing requirements at each stage plays a key role in quality control
and improves both environmental and economic performance of production.
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