Urban mining・Minor metal sludge drying, Low-temperature drying for recycling of minor metal sludge/ Test cases / Sludge drying, Recycling drying

Summary

The Challenge of Resource Dependence:

• Japan heavily relies on imported mineral resources.
• Securing these resources, especially minor and precious metals, is crucial for its international competitiveness.
• Recycling minerals from sludge is a promising solution to reduce reliance on imports and protect the environment.
• Phosphorus, a critical mineral, is also being targeted for recovery from sewage sludge.

The Solution: KENKI DRYER

• KENKI DRYER is a unique, patented drying technology designed to efficiently and effectively dry various materials, including sludge.
• It addresses the challenges of drying lumpy and sticky materials by crushing and reducing their surface area.
• By using low-temperature, steam-based indirect drying, KENKI DRYER minimizes damage to the material’s properties, enabling its reuse and recycling.
• This technology offers significant environmental benefits, including reduced carbon emissions and energy consumption.
• It is easy to operate, maintain, and highly durable, making it a cost-effective solution for businesses.

In essence, KENKI DRYER is a cutting-edge technology that contributes to resource security, environmental sustainability, and industrial efficiency.

Japan is almost 100% dependent on imports for its mineral resources. In the future, minor metals and precious metals in particular will continue to be important resources, and securing these resources is essential to maintaining and strengthening international competitiveness. One of the measures to secure mineral resources is the reuse and recycling of minerals contained in sludge, which will contribute to environmental protection and reduce greenhouse gas emissions. Phosphorus, which is currently imported from China, is also an indispensable mineral. Therefore, the extraction of phosphorus from sewage sludge is being promoted as a national project.
The reuse and recycling of sludge from wastewater treatment plants is becoming increasingly important for environmental protection, decarbonization and securing resources that are currently dependent on imports.

After dehydration, many of the dried sludge objects, whether organic or inorganic, are found in a lumpy form. With KENKI DRYER, the dried objects such as lumpy sludge are crushed to some extent inside the dryer, and by reducing the surface area, drying can be carried out thoroughly even inside the dried objects. Even with clumpy dried objects, there are cases where the adhesive quality is strong during drying and clogging occurs inside the dryer, and the dried objects cannot be discharged, but with KENKI DRYER, the unique mechanism of the world patent prevents clogging inside the dryer, and the dried objects can be dried smoothly.

In addition, sludge discharged from wastewater treatment plants tends to form lumps during the drying process due to the effect of flocculants used in wastewater treatment. When the material to be dried forms lumps, the heat does not spread sufficiently throughout the material and the inside of the material does not heat up, so only the surface dries and the inside does not heat up and dry. Even if the material to be dried forms lumps, the KENKI DRYER can dry the inside of the material sufficiently by crushing and reducing the size of the material to some extent inside the dryer and reducing the surface area.

By drying the sludge discharged from wastewater treatment plants at low temperatures, the components of the sludge change little after drying, making it possible to use it as a compost, soil conditioner, fuel, etc. as an upcycled product. KENKI DRYER uses steam as a heat source for indirect drying at low temperatures, so the components of the dried material change little after drying, making it possible to use it as an upcycled or recycled product.

KENKI DRYER, which has 11 patents in 8 countries, is a steam indirect dryer, but it is a completely unique product with a different structure from other steam indirect dryers. Direct-fire dryers, such as those that use burners, emit carbon dioxide, which is bad for the environment and goes against the trend of decarbonization. Because they dry at high temperatures, they use a lot of fuel and their parts wear out quickly, making them expensive to maintain.
KENKI DRYER uses steam as a heat source, but because of its high drying heat efficiency, it only needs a small amount of steam, so you can use the steam you’re currently using, and if you use excess or surplus steam, you don’t have to pay for fuel. The dryer doesn’t emit carbon dioxide when it dries, so you can dry without carbon dioxide. Alternatively, by installing an electric or hydrogen fuel boiler, there is no emission of global warming gases or carbon dioxide CO2 during the drying process.
In addition, there are no problems after start-up, and the rotation speed of the dryer’s main body blades is very slow at less than 5 rpm, so there is little wear and tear on parts, and maintenance is easy and inexpensive. KENKI DRYER is a continuous drying system, in which the drying material to be dried is stored, rather than a batch system. Therefore, operation is simple and unmanned operation is possible 24 hours a day.

If you have any questions or concerns, please let us know. We will be happy to suggest the best dryer for your company’s needs.
Our dryer, ‘KENKI DRYER’, has received 11 patents in 8 countries and is particularly effective at drying sticky materials that others cannot handle. It has no installation problems, is easy to maintain, and has low operating costs. The KENKI DRYER has been well received by companies that have installed it due to its uniform drying, improved productivity with less manpower, high performance and durability.

KENKI DRYER, which can dry sticky and adhesive materials that others cannot, is a breakthrough dryer with a total of 11 patents (2 in Japan and 9 in 7 foreign countries) and proprietary technology. Please consider KENKI DRYER for your high moisture organic waste dryer, sludge dryer, slurry dryer, methane fermentation digested liquid dryer, waste upcycling and recycling dryer.
KENKI DRYER has been granted 11 patents in 8 countries (Japan, Taiwan, USA, France, Germany, UK, Switzerland, Canada).

KENKI DRYER is an excellent choice for minor metal sludge dryers due to several key advantages:

1. Low-Temperature Drying:

• Preserves Material Integrity: KENKI DRYER uses low-temperature steam drying, which minimizes compositional changes in the sludge. This is crucial for preserving the valuable minor metals within the sludge, ensuring they can be effectively recovered in subsequent processing steps.
• Energy Efficiency: Low-temperature drying reduces energy consumption compared to high-temperature methods, making it a more cost-effective and environmentally friendly solution.

2. Efficient Drying of Lumpy Sludge:

• Unique Crushing Mechanism: KENKI DRYER’s innovative design effectively breaks down lumpy sludge, increasing the surface area for efficient drying. This prevents uneven drying and ensures thorough moisture removal.
• Clogging Prevention: The patented mechanism prevents clogging, ensuring smooth operation and maximizing drying efficiency.

3. Continuous Operation and Low Maintenance:

• 24/7 Operation: KENKI DRYER enables continuous operation, maximizing productivity and reducing downtime.
• Low Maintenance: The slow rotation speed of the dryer’s blades and the use of durable materials minimize wear and tear, reducing maintenance costs.

4. Environmental Benefits:

• Reduced Carbon Footprint: Low-temperature drying and the potential for using renewable energy sources contribute to a reduced carbon footprint.
• Resource Recovery: By enabling efficient drying and subsequent processing, KENKI DRYER supports the recovery of valuable minor metals, reducing the need for mining and contributing to a more sustainable future.

In summary, KENKI DRYER’s combination of low-temperature drying, efficient handling of lumpy sludge, continuous operation, and environmental benefits makes it an ideal choice for minor metal sludge dryers. It helps to maximize resource recovery, minimize environmental impact, and improve overall operational efficiency.

KENKI DRYER is chosen for recycling dryers because it efficiently dries high-moisture materials while preserving their composition, enabling their reuse in various applications such as compost, fuel, or other recycled products. Its low-temperature, steam-based drying process minimizes environmental impact by emitting no CO2 and supports decarbonization efforts. The dryer’s patented design prevents clogging, handles sticky materials effectively, and offers reliable, continuous operation with low maintenance and operating costs. These features make it ideal for recycling and upcycling processes.

KENKI DRYER is chosen for sludge dryers due to its ability to handle a wide range of sludge types, including sticky, adhesive, and high-moisture materials. Its steam-based, low-temperature drying process ensures minimal changes to the sludge composition, making it suitable for reuse in applications like compost, soil conditioners, or fuel. The dryer prevents clogging through its unique patented mechanism and efficiently crushes and reduces the size of sludge lumps, ensuring thorough drying.
Additionally, the KENKI DRYER is eco-friendly, emitting no CO2 during operation, and can utilize surplus steam, lowering energy costs. Its slow-rotating blades minimize wear and tear, reducing maintenance needs and operational costs. With continuous, automated operation, the dryer is highly productive and reliable, making it a preferred choice for sludge drying in various industries.

• Material to be dry: Urban mining, Minor metal sludge
• Purpose of drying: Recycling, Reducing industrial waste cost and amount
• Moisture content: 79.3％W.B. before drying, 18.6％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

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

“Minor metal sludge” refers to the residual byproducts or waste material that contains minor metals. These minor metals are elements that are not commonly found in large quantities but have significant industrial value. Examples include rare earth elements, indium, gallium, and others used in high-tech applications such as electronics, renewable energy, and aerospace.

The term “sludge” indicates that these metals are in a semi-solid or liquid state, often mixed with other substances. This sludge is typically produced during the processing, refining, or recycling of materials containing minor metals. Proper management and recycling of minor metal sludge are crucial because these metals are valuable and sometimes scarce, making their recovery important for both economic and environmental reasons.

Source：ChatGPT

Inorganic sludge is a type of sludge that is primarily composed of non-organic materials. These materials are typically minerals, metals, and other inorganic substances. Unlike organic sludge, which contains a high percentage of organic matter like bacteria and food scraps, inorganic sludge is more likely to contain sand, grit, and other solid particles.

Common sources of inorganic sludge include:

• Industrial wastewater: Wastewater from factories and manufacturing processes often contains inorganic contaminants.
• Stormwater runoff: Stormwater can carry sand, grit, and other inorganic debris into wastewater treatment plants.
• Construction sites: Construction activities can generate significant amounts of inorganic sludge.

Inorganic sludge is often denser and heavier than organic sludge and may require different treatment and disposal methods. It can be a challenge to remove and dispose of effectively due to its inorganic composition.

Source：Gemini

The primary difference between precious metal sludge and inorganic sludge lies in their composition and the value of the materials they contain.

Precious metal sludge typically contains a significant amount of precious metals, such as gold, silver, platinum, palladium, rhodium, iridium, and osmium. These metals are valuable due to their rarity, durability, and aesthetic appeal. The recovery of precious metals from sludge is often economically viable and environmentally responsible.

Inorganic sludge is a broader term that encompasses a variety of sludges containing inorganic materials, which are non-living substances that do not contain organic matter. These sludges can originate from various sources, including wastewater treatment plants, industrial processes, and mining operations. While inorganic sludges may contain valuable materials, they generally do not contain precious metals in significant quantities.

Key differences summarized:

• Composition: Precious metal sludge contains valuable precious metals, while inorganic sludge may contain a variety of inorganic materials.
• Value: Precious metal sludge is typically more valuable due to the high value of the precious metals it contains.
• Recovery: The recovery of precious metals from sludge is often economically viable, while the recovery of materials from inorganic sludge may be less profitable.

In summary, precious metal sludge is a specific type of inorganic sludge that is characterized by the presence of valuable precious metals. While both types of sludge can have environmental and economic implications, the value and recovery potential of precious metal sludge are generally higher.

Source：Gemini

Inorganic and organic sludge are two primary types of sludge produced during wastewater treatment processes. They differ significantly in their composition, properties, and disposal methods.

Inorganic Sludge

• Composition: Primarily consists of inorganic materials such as sand, grit, and metal particles.
• Sources: Wastewater from industrial processes, construction sites, and stormwater runoff.
• Properties: Typically denser, heavier, and less biodegradable than organic sludge.
• Disposal: Often disposed of in landfills or used as fill material in construction projects.

Organic Sludge

• Composition: Contains a high percentage of organic matter, including bacteria, viruses, and suspended solids.
• Sources: Domestic wastewater, food processing wastewater, and agricultural runoff.
• Properties: More biodegradable and can generate methane gas during anaerobic decomposition.
• Disposal: Can be treated through anaerobic digestion to produce biogas, composted, or landfilled.

Key Differences:

Feature	Inorganic Sludge	Organic Sludge
Composition	Inorganic materials	Organic matter
Source	Industrial, construction	Domestic, food processing
Properties	Dense, heavy, non-biodegradable	Biodegradable, generates methane
Disposal	Landfills, fill material	Anaerobic digestion, composting, landfills

In summary, inorganic sludge is primarily composed of inorganic materials and is often disposed of in landfills, while organic sludge contains a high percentage of organic matter and can be treated or composted. Understanding the differences between these two types of sludge is crucial for proper wastewater treatment and disposal.

Source：Gemini