Drying of urban mining, precious metal sludge for recycling / Test cases / Sludge drying, sludge dryer

Summary

■Japan relies almost 100% on imports for mineral resources, and precious and minor metals, known as urban mines, are particularly important.
Japan relies almost 100% on imports for mineral resources, and precious metals and minor metals, known as urban mines, are particularly important for maintaining and strengthening its international competitiveness.

■Re-use and recycling of minerals in sludge is important: it contributes to environmental protection and greenhouse gas reduction.
It is important to re-use and recycle minerals contained in sludge as one of the measures to secure mineral resources. This is an initiative that contributes to environmental protection and reduces greenhouse gases.

■KENKI DRYER: a revolutionary drying system
KENKI DRYER is a revolutionary drying device that overcomes the challenges of conventional drying equipment.

・Smoothly dries even lumpy sludge
A unique crushing mechanism reduces the size of lumpy sludge and increases its surface area, allowing it to dry sufficiently all the way to the inside.
It can also be used for sludge that tends to become lumpy due to the effects of flocculants generated at wastewater treatment plants.

・Low-temperature drying suppresses compositional changes
Low-temperature drying with steam minimizes compositional changes after drying, making it suitable for recycling and upcycling.

・Suitable for sludge with strong adhesion and stickiness
A unique, world-patented mechanism prevents clogging inside the dryer and ensures smooth drying even of sludge with strong adhesion and high water content.

・Continuous operation reduces running costs
Continuous operation is possible, requiring no manpower and operating 24 hours a day.
Low-temperature drying and low rotation of the blades extend component life, reduce steam consumption and lower running costs.

■KENKI DRYER patents
KENKI DRYER has been granted a total of 11 patents, two in Japan and nine in seven foreign countries.

■Advantages of sludge drying

・Reduction of industrial waste volume and industrial waste costs
Drying sludge reduces its weight and the amount of industrial waste. It also contributes to reducing industrial waste costs, which have been rising in recent years.

・Environmental protection
Proper treatment of sludge prevents environmental pollution and contributes to environmental protection.

■KENKI DRYER: Technology that contributes to securing mineral resources and protecting the environment
KENKI DRYER is an innovative technology that contributes to securing mineral resources and protecting the environment. It efficiently recovers and recycles minerals in sludge, helping to realize a sustainable society.

Japan is almost 100% dependent on imports for its mineral resources. In the future, precious metals and minor metals, known as urban mining, will continue to be particularly important resources, and it is essential to secure these resources in order to maintain and strengthen international competitiveness. The reuse and recycling of minerals contained in sludge is one of the measures to secure mineral resources and is important because it contributes to environmental protection and the reduction of greenhouse gases.

In the drying process of KENKI DRYER, lumpy sludge and other materials to be dried are crushed to a certain extent inside the dryer to ensure smooth drying without clogging the machine. their surface area, which allows drying to the inside of the dried materials to a sufficient extent. Even lumpy materials to be dried can become clogged inside the dryer during drying due to their strong adhesive properties, but KENKI DRYER’s unique, world-patented mechanism ensures smooth drying without clogging the machine.

Sludge discharged from wastewater treatment plants tends to become lumpy during the drying process due to the coagulant used in wastewater treatment. In the drying process of KENKI DRYER, even if the dried material becomes lumpy, it is crushed to a certain extent in the dryer and the surface area is reduced to a smaller size, so that the drying process is more than sufficient to dry the inside of the dried material. The drying process is more than sufficient to dry even the inner part of the dried material.

KENKI DRYER dries sludge discharged from wastewater treatment plants at low temperatures so that the composition of the dried material changes little after drying and can be used as a recycled or upcycled product. The KENKI DRYER can be fully utilized as a recycled or upcycled product.

Even materials that are difficult to dry due to their strong adhesion and stickiness can be dried easily and smoothly with the KENKI DRYER. For example, sludge that is highly adhesive and sticky is difficult to dry. Depending on the type of dryer, sludge may clog inside the dryer during drying and not be discharged, but the KENKI DRYER’s unique, world-patented mechanism ensures that even highly adhesive and sticky sludge with high water content can be dried smoothly without clogging inside the dryer. In addition, the KENKI DRYER is a continuous low-temperature drying system, which means that the composition of the dried material does not change so much after drying, making it suitable for a variety of uses and allowing it to operate unattended 24 hours a day.

KENKI DRYER is a revolutionary drying system with a total of 11 patents, 2 in Japan and 9 in 7 foreign countries.
The capabilities of the KENKI DRYER are also fully demonstrated when drying raw material slurries with strong adhesion and stickiness, and no matter how strong the adhesion and stickiness, the dryer can operate stably without clogging the inside of the dryer. The low-temperature drying process does not change the composition of the material being dried, so there are no problems with drying raw materials. The dryer is a continuous dryer, so it does not require manpower for drying and can operate unmanned 24 hours a day.

Drying sludge to reduce its weight and the amount of industrial waste can help reduce industrial waste costs, which are rising due to the recent 2024 trucking issue, and most importantly, protect the environment.

Maintenance is easy as there are no problems once the machine is up and running. The low temperature drying and the low speed of the blades in the main unit (less than 5 rpm) mean that the parts last longer, and steam consumption is low because steam from the heat source is not fed into the blades, so running costs are low.

Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Precious metals, particularly the noble metals, are more corrosion resistant and less chemically reactive than most elements. They are usually ductile and have a high luster. Historically, precious metals were important as currency but are now regarded mainly as investment and industrial raw materials. Gold, silver, platinum, and palladium each have an ISO 4217 currency code.

Source：Wiki Precious metal

The term “minor metal” refers to a broad range of metals that are not traded on formal exchanges, such as the London Metal Exchange (LME). These metals are often extracted as by-products of base metal smelting and have relatively low annual production volumes compared to base metals. They are used in various high-tech applications, including electronics, solar panels, and batteries.

Some examples of minor metals include tungsten, titanium, cobalt, molybdenum, indium, niobium, and rare-earth elements. These metals are critical to modern technology and are used in a wide range of industries, including pharmaceuticals, semiconductors, automotive, glass, and solar energy.

Source：Perplexity

An urban mine is the stockpile of rare metals in the discarded waste electrical and electronic equipment (WEEE) of a society. Urban mining is the process of recovering these rare metals through mechanical and chemical treatments. In 1997, recycled gold accounted for approximately 20% of the 2700 tons of gold supplied to the market.

The name was coined in the 1980s by Professor Hideo Nanjyo of the Research Institute of Mineral Dressing and Metallurgy at Tohoku University and the idea has gained significant traction in Japan (and in other parts of Asia) in the 21st century.

Research published by the Japanese government’s National Institute of Materials Science in 2010 estimated that there were 6,800 tones of gold recoverable from used electronic equipment in Japan.

Source：Wiki Urban mining

Mineral resources are naturally occurring, solid, inorganic substances with a specific chemical composition and a characteristic crystal structure. They are essential for our modern way of life. Over 95% of the energy we use, 80% of industrial raw materials, and 70% of raw materials for agriculture come from mineral resources.
There are over 2,000 identified minerals, and they can be broadly classified into two categories: metals and non-metals.

Metals are lustrous, ductile, and malleable. They are good conductors of heat and electricity. Examples of metals include iron, copper, gold, and silver.

Non-metals are all minerals that are not classified as metals. They have a wide variety of properties and are used in a wide variety of applications. Examples of non-metals include diamond, sulfur, salt, and limestone.

Source：Gemini

Sludge is a semi-solid slurry that can be produced from a range of industrial processes, from water treatment, wastewater treatment or on-site sanitation systems. It can be produced as a settled suspension obtained from conventional drinking water treatment, as sewage sludge from wastewater treatment processes or as fecal sludge from pit latrines and septic tanks. The term is also sometimes used as a generic term for solids separated from suspension in a liquid; this soupy material usually contains significant quantities of interstitial water (between the solid particles). Sludge can consist of a variety of particles, such as animal manure.

Source：Wiki Sludge

• Material to be dry: Urban mining, Precious metal sludge
• Purpose of drying: Recycling, Reducing industrial waste cost and amount
• Moisture content: 79.2％W.B. before drying, 9.3％W.B. after drying
• Requirements for dryer: Drying is carried out inwards as the dried material is lumpy and heat does not penetrate easily into the interior. To prevent clogging inside the dryer caused by the stickiness and adhesiveness. Automated continuous operation with no operator attended.
  Machine cost can be recovered in short term.
• Test result: OK

Sludge drying

Competitive comparison

One of the International Patented Technology that KENKI DRYER has is a self-cleaning structure called Steam Heated Twin Screw technology (SHTS technology). No matter how materials are sticky, adhesive and viscous is, they can be dried without clogging inside of the dryer because of this unique structure that no other products has.
For example, even materials stuck to the blades of one screw, blades of the other screw in the dryer’s body forcibly peels the materials off as they rotate. Since the blades rotate by peeling the material off each other, any sticky, adhesive and viscous material does not adhere to the blade, and the blades continue rotating, peeling, agitating and heating material without stopping while they carries material further. Also, since surface of blades are always renewed and kept clean, heat near the blades is not blocked and it is conducted directly into the materials.

Self-cleaning screw

KENKI DRYER has three main characteristics. They are 1) Any materials can be dried as expected including sticky, adhesive and viscous materials and raw material slurry that no other company can deal with, 2) dried material can by recycled or utilized as raw materials because of its low-temperature drying method, and 3) there is no need to assign operator since its continuous operating system makes 24 hours unattended operation possible.

Products

The unique and original drying mechanism of KENKI DRYER is also International Patented Technology. Because 4 drying mechanisms which are crashing drying, agitation drying, circulation drying and indirect drying work simultaneously and add heat to material being dried repeatedly and continuously, inner part of the material is dried thoroughly and quality of discharged material after drying is stable. This series of drying mechanisms prevents agglomeration which causes insufficient drying from feeding process of the material into the dryer until discharging process after drying completed. Various ingenuities to conduct heat surely into inner part of the materials are exercised and stable heating and drying are proceeded continuously.

Methods

Even KENKI DRYER uses only saturated steam as its heat source, it is outstanding in safety and hygiene point of view with its unique drying mechanism based on combined use of conductive heat transfer method and heated air method. Since steam is a stable heat source, quality of discharged material after drying is also stable and equable. Maximum allowed steam pressure is 0.7Mpa and adjustment of steam pressure, adjustment of drying temperature in other words, can be easily done. Saturated steam is commonly used in many factories so that it can be said as a familiar and handy heat source. In comparison with drying methods using burner or hot blasts, saturated steam method is an indirect drying applying heat exchange via pipes that steam is passing through, therefore, it hardly burns the materials and is outstanding in safety and hygiene point of view.

Heat source, Steam