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

Summary

KENKI DRYER is a unique, low-temperature drying system designed for various types of sludge, including those from wastewater treatment plants. Its patented technology ensures efficient drying without clogging, even for lumpy materials. By drying at low temperatures, the dryer preserves the composition of the sludge, making it suitable for recycling and upcycling.

Key features and benefits of KENKI DRYER:

• Unique drying mechanism: Prevents clogging and ensures efficient drying of lumpy sludge.
• Low-temperature drying: Preserves sludge composition for recycling and upcycling.
• High drying efficiency: Reduces steam consumption and carbon emissions.
• Low maintenance: Slow rotating blades minimize wear and tear.
• Continuous operation: Enables unmanned operation 24/7.
• Environmental benefits: Contributes to waste reduction, decarbonization, and resource conservation.

KENKI DRYER offers a sustainable solution for sludge drying and waste management, aligning with the growing demand for resource efficiency and environmental protection.

Japan is almost 100% dependent on imports for its mineral resources. In the future, precious metals and rare 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.

In the drying process of the KENKI DRYER, lumpy sludge and other dried materials are crushed to a certain extent inside the dryer to reduce their surface area, which allows sufficient drying to occur inside the dried materials. Even lumpy dried materials may not be discharged because of clogging inside the dryer due to strong adhesion during drying, but KENKI DRYER’s world-patented unique mechanism prevents clogging inside the dryer and enables smooth drying.

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 the KENKI DRYER, even if the dried sludge becomes lumpy, it is crushed to a certain extent in the dryer to reduce its surface area, which allows the dried sludge to be dried more than adequately. This allows the dried material to be dried to the inside of the dryer.

KENKI DRYER dries sludge discharged from wastewater treatment plants at low temperatures so that the composition of the dried materials remains unchanged after drying and can be recycled and upcycled. It can be fully utilized as recycled and upcycled products.

KENKI DRYER, with 11 patents in 8 countries, is an indirect steam dryer, but it is a completely unique product, different in structure from other similar indirect steam dryers. The KENKI DEYER uses steam as a heat source, but its high drying heat efficiency means that less steam is used. The use of excess steam is not costly in terms of fuel costs, and the dryer does not emit carbon dioxide during the drying process, allowing for decarbonized drying. Alternatively, by installing an electric boiler, no greenhouse gases or CO2 emissions are produced during drying.

The dryer’s blades rotate at a very slow speed of 5 rpm or less, which means that wear on parts is minimal and maintenance is easy and inexpensive.
KENKI DRYER is a continuous dryer, not a batch dryer that stores materials to be dried. Therefore, operation is simple and unmanned operation is possible 24 hours a day.

Drying sludge to reduce the weight and volume of waste products can contribute to environmental protection and decarbonization by reducing the cost of industrial waste, which is rising due to the recent trucking problem in 2024, and by reducing the number of trucks used to transport waste, thereby reducing carbon dioxide emissions.

Currently, there is a shortage of wood in Japan. The use of dried organic waste as fuel instead of wood, or the use of dried organic sludge as biochar or biocoke by carbonization, is attracting much attention. For example, bio-coke can be used as a reductant or deoxidizer to replace coke in the steel and foundry industries.
Biochar and bio-coke are carbonized materials made from biological resources that are effective in revitalizing organisms and improving the environment. We can provide carbonization services using our Biogreen pyrolysis equipment, which does not use fossil fuels and does not emit CO2, a greenhouse gas, so please contact us.

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 chosen for drying precious metal sludge due to several key advantages:

1. Preservation of sludge composition: The low-temperature drying process of KENKI DRYER ensures that the precious metals within the sludge remain intact, preventing any loss or degradation during drying. This is crucial for the subsequent recovery and recycling of these valuable metals.

2. Efficient drying: The unique drying mechanism of KENKI DRYER effectively removes moisture from the sludge, ensuring that the dried material is suitable for further processing. This efficiency contributes to the overall cost-effectiveness of the precious metal recovery process.

3. Prevention of clogging: The patented technology in KENKI DRYER prevents clogging during the drying process, even when dealing with lumpy or sticky sludge. This ensures smooth operation and minimizes downtime.

4. Environmental friendliness: KENKI DRYER’s low-temperature drying process and reduced steam consumption contribute to a more sustainable and environmentally friendly precious metal recovery operation.

5. Versatility: KENKI DRYER is not only suitable for drying precious metal sludge but can also be used for other types of sludge and wet materials, making it a versatile and valuable asset for various industrial applications.

Overall, KENKI DRYER’s ability to preserve sludge composition, dry efficiently, prevent clogging, and operate in an environmentally friendly manner makes it an ideal choice for drying precious metal sludge.

KENKI DRYER is a recycling dryer that is chosen for its unique technology and high performance. It is able to effectively dry various types of waste materials, including those with strong adhesion or stickiness, which were difficult to process with conventional dryers.

Key reasons why KENKI DRYER is chosen:

• Effective drying of sticky and adhesive sludge: KENKI DRYER can efficiently dry various types of waste materials, including sticky and adhesive sludge, which were difficult to process with conventional dryers.
• Low temperature drying with minimal component changes: The low temperature drying process in KENKI DRYER minimizes changes to the components of the dried material, allowing it to be reused for various purposes such as raw materials, fuel, and soil improvement.
• High thermal efficiency and low running costs: The use of saturated steam as a heat source results in high thermal efficiency and reduced fuel costs. Additionally, the machine has low component wear and tear, leading to lower maintenance costs.
• Continuous operation without manual intervention: KENKI DRYER can operate continuously for 24 hours without manual intervention, contributing to labor savings.
• Wide range of applications: It can handle various types of waste materials, including sludge, slurry, and methane fermentation digested liquid.
• Reduced environmental impact: By reducing waste volume and promoting recycling, KENKI DRYER contributes to reducing environmental impact.

Three key features of KENKI DRYER:

1. Effective drying of sticky and adhesive materials: The unique patented technology in KENKI DRYER prevents clogging inside the machine, even with highly sticky and adhesive materials.
2. Low temperature drying and high thermal efficiency: The use of saturated steam for low temperature drying minimizes component changes and ensures high thermal efficiency.
3. Continuous drying: KENKI DRYER can operate continuously for 24 hours without manual intervention.

Additional reasons why KENKI DRYER is chosen:

• Drying process: The drying process in KENKI DRYER is optimized based on the type and condition of the waste material.
• Four types of drying mechanisms: KENKI DRYER has four types of drying mechanisms to accommodate various types of waste materials.
• Why it is difficult to dry sludge: Drying sludge offers various benefits, including reduced volume and potential for reuse.

Summary:

KENKI DRYER is chosen by many companies as a recycling dryer due to its high performance and wide range of applications. It is particularly effective in drying waste materials that were difficult to process with conventional dryers.

KENKI DRYER is chosen for drying sludge due to several key advantages:

1. Unique drying mechanism: The patented technology in KENKI DRYER ensures efficient drying without clogging, even for lumpy or sticky sludge. This is particularly beneficial for sludge from wastewater treatment plants, which often has a challenging consistency.

2. Low-temperature drying: The dryer operates at low temperatures, preserving the composition of the sludge. This allows for the recovery of valuable materials like phosphorus and prevents the formation of harmful byproducts.

3. High drying efficiency: KENKI DRYER uses steam as a heat source but achieves high drying efficiency, reducing steam consumption and lowering operating costs.

4. Environmental friendliness: The dryer’s low-temperature operation and reduced steam consumption contribute to a more sustainable and environmentally friendly sludge drying process.

5. Versatility: KENKI DRYER can handle various types of sludge, including those from different industries and wastewater treatment plants. This versatility makes it a valuable asset for a wide range of applications.

6. Cost-effective: The dryer’s efficient operation and low maintenance requirements contribute to a cost-effective solution for sludge drying.

Overall, KENKI DRYER’s unique features, environmental benefits, and versatility make it an ideal choice for drying sludge in various industries, particularly those focused on sustainability and resource recovery.

• 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

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 lustre. 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.

The best known precious metals are the precious coinage metals, which are gold and silver. Although both have industrial uses, they are better known for their uses in art, jewelry, and coinage. Other precious metals include the platinum group metals: ruthenium, rhodium, palladium, osmium, iridium, and platinum, of which platinum is the most widely traded. The demand for precious metals is driven not only by their practical use but also by their role as investments and a store of value. Historically, precious metals have commanded much higher prices than common industrial metals.

Source：Wiki precious metal

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

Precious metal sludge is a byproduct of various industrial processes that involves the use or recovery of precious metals. It typically consists of a mixture of precious metals, other metals, and non-metallic materials suspended in a liquid or slurry form.

Common sources of precious metal sludge include:

• Jewelry manufacturing: Waste materials from the cutting, polishing, and casting of precious metal jewelry.
• Electronic recycling: Residues from the dismantling and processing of electronic devices containing precious metals, such as gold, silver, and platinum.
• Chemical refining: Byproducts from the refining of precious metals from ores or other materials.
• Electroplating: Waste solutions from the electroplating of precious metals onto other surfaces.

Precious metal sludge can be a valuable resource due to the presence of precious metals, which can be recovered through various refining processes. However, it also poses environmental concerns if not properly managed, as it can contain hazardous substances and contaminants.

Proper handling and disposal of precious metal sludge is essential to minimize environmental risks and maximize the recovery of valuable materials.

Source：Gemini

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

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