Ashio Copper Mine

Once known as “Japan’s No. 1 mining town,” this copper mine has a prosperous history. Visitors can tour the mine shafts. After the mine was closed, some of the tunnels were opened to the public, and visitors ride a trolley train through the dimly lit tunnels, where realistic dolls recreate the ore mining process of that time.

There is also a museum, including a “Copper Museum,” where the copper smelting process and other exhibits are displayed. There is also a rest house on the premises.

Night tours are held every August, and visitors can enjoy hands-on events unique to the Ashio Copper Mine.

The Ashio Copper Mine Museum was established in 1980, utilizing the former mine shafts of the Ashio Copper Mine. Visitors can tour the 700-meter-long tunnel by riding the underground train.

Along the way, 39 dolls are used to recreate the scene of copper mining, and the Ashio Copper Mine Memorial Museum and Rest House are also located in front of the entrance to the tunnel.

The Ashio Copper Mine flourished as a copper mine under the direct control of the Edo shogunate since the first discovery of copper at Bizen Tateyama in 1610, and was privatized in 1877 by Ichibei Furukawa, and rapidly developed into the largest copper mine in Japan with the latest technology and facilities.

Today, part of the mine is open to the public as part of Ashio Copper Mine tourism, where visitors can learn about the mine’s history and how it works.

Ashio Copper Mine was located in the Ashio district of Nikko City, Tochigi Prefecture. It was once designated as a national historic site as the “Ashio Copper Mine Site.

The Ashio Copper Mine is said to have been discovered in 1550. In 1610, two peasants discovered a deposit of ore, and full-scale mining began as a mine under the direct control of the Edo shogunate. The shogunate established a foundry in Ashio, and the copper mine prospered, leading to the development of a town known as “Ashio Senken. The copper mined was used for construction materials for Nikko Toshogu Shrine and Zojoji Temple in Edo (Tokyo), and a representative currency called Kan’ei Tsuho was also minted. During the Edo period, copper production peaked at 1,200 tons per year. However, mining volume declined sharply for a period of time, and the mine was almost completely closed from the end of the Edo period to the beginning of the Meiji era (1868-1912). The mine was privatized in 1871, but copper production dropped to 150 tons per year.

While many were pessimistic about the future of the Ashio Copper Mine, Ichibe Furukawa began operating the mine in 1877, and after several years of unsuccessful efforts, a promising vein of ore was discovered in 1881. Thereafter, advances in exploration technology led to the discovery of one promising vein after another. After Ichibei Furukawa’s death, the company organization was established as Furukawa Mining in 1905. Against the backdrop of the Meiji government’s policy of national wealth and military strength, the Ashio Copper Mine, together with the Hitachi Mine and the Besshi Copper Mine, achieved rapid development and grew to become a major copper mine, accounting for 40% of Japan’s copper production in the early 20th century.

However, the development of the mine and the smelting business had a dark side. Trees in the Ashio Mountains were cut down and used as mine timber and fuel, and the smoke emitted from the ore smelting plants caused air pollution. The devastation of the Ashio Mountains caused frequent flooding of the Watarase River, and waste from the mining operations flowed down the river, spreading water and soil pollution and causing large-scale environmental contamination (pollution). This incident, known as the “Ashio Mining Poisoning Incident,” became a major political issue when Shozo Tanaka raised the issue in the Diet in 1891, and although mining prevention work and repair work on the Watarase River were undertaken beginning in the 1890s, the damage caused by mining pollution remained unresolved.

In 1973, mining operations were halted and the Ashio Copper Mine was closed. The total length of tunnels dug for mine development reached 1,234 kilometers. After the mine closed, the smelting operations continued in part because the company’s own hydroelectric power plant and industrial water used water from the mountainside, but in 1989 the JR Ashio Line freight Ashio Copper Mine (Ashio Dozan), located in the Ashio district of Nikko City, Tochigi Prefecture, became a historical copper mine. The Ashio Copper Mine site is designated as a national historic site and visitors can visit its venerable heritage.

The Ashio Copper Mine was discovered in 1550, and from 1610, full-scale mining operations were conducted as a mine under the direct control of the Edo shogunate. The shogunate established a coin foundry in Ashio, and the copper mine prospered, so much so that the town of Ashio was called “Ashio Senken” (Ashio Thousand Houses). The copper mined was used for Nikko Toshogu Shrine and Zojoji Temple, and was also minted as Kan’ei Tsuho. During the Edo period (1603-1867), the mine produced 1,200 tons of copper annually, but the amount of copper mined declined for a time and the mine was closed from the end of the Edo period to the beginning of the Meiji period (1868-1912). Later, Ichibei Furukawa took over management of the mine, and in 1881, a promising vein of ore was found. Technological advances led to the discovery of one vein after another, and the Ashio Copper Mine developed into one of the leading copper mines in Japan.

However, environmental problems also existed behind the development of the mine and the smelting business. Air pollution caused by timber cutting and smoke emissions from the mine operations became a problem. The devastation of the Ashio Mountains caused frequent flooding of the Watarase River, and the waste from the mining operations flowed into the river, polluting the water and soil in the surrounding areas. This is known as the “Ashio Mine Poisoning Incident.

Mining at the Ashio Copper Mine ceased in 1973, marking the end of the mine’s history. Some of the facilities were still used for recycling industrial waste, but the smelting operations ceased. However, the “Ashio Copper Mine Sightseeing” facility was opened to convey the history of the Ashio Copper Mine, and visitors can take a trolley ride through the tunnels. Also nearby is the Furukawa Ashio History Museum, where visitors can learn about the history of the Ashio Copper Mine, including the Ashio Mine Poisoning Incident.

The Ashio Copper Mine is a copper mine with a rich history that has attracted attention for both its development and environmental issues.

Pollution

In addition to the damage caused by sulfurous acid (sulfurous acid gas), the surrounding forests were devastated by logging, wildfires caused by population growth, and logging to secure firewood and coal. The mine was not quieted down until 1956, when self-melting was introduced, and a mine control project is still underway today.

Mine

There is one copper mine called Bizen Tateyama, but other mines did not produce copper.

Mines

There are three mine entrances: Motoyamakeng (Arikikeng), Kotakikeng, and Tongdokeng. The Kotaki-keng is connected in a straight line from the Bonsan-keng, while the Tongdokeng tunnel is connected to this thicker tunnel from the side. As a result, the tunnel connecting the three tunnels is T-shaped. The Kotaki-keng was closed in 1954, and the last two tunnels to be used were the Bonsan-keng and the Tongdong-keng. In fact, there was a subtle difference in the location of the Bensankeng and Arikikeng, and there were other main tunnels in close proximity. Usually, these three shafts are collectively referred to as “Motoyakeng. Ariki Keng was initially called Likikeng, but was changed to Ariki for good luck. There is also a tunnel mouth called Sumikoqiao. It is small in size and is considered almost the same as the Tongdongkeng, but it was nominally independent. It existed near the present-day Sumashiqiao Deposit Site.

Ore dressing plant

Located in the Tongdong area. In 1918, a flotation method was introduced to sort the ore into a fine powder using a ball mill, and although the ore was collected by a thickener, the Watarase River became cloudy.

Smelters

The largest smelter was located in the Motoyama area, and there were also smaller smelters in the Kotaki area. Copper was smelted from the ore, and after the 1960s, sulfuric acid was produced by collecting sulfurous acid gas generated during smelting, which was also shipped.

Water Purification Plant

In 1897, the government ordered the water from Ashio’s mining facilities to be precipitated as a measure to prevent mineral poisoning (Second Prevention Order). After the mine closed, water purification facilities continued to operate, with two still in operation as of 2007: the Motoyama Water Purification Plant and the Nakasai Water Purification Plant. There was also a water purification plant in Kotaki, but it was integrated into the Nakasai plant due to its small size. Ashio Copper Mine had five official drainage outlets: the refining plant drainage outlet, the refining karami drainage outlet, the Motoyama water purification drainage outlet, the Nakasai water purification drainage outlet, and the Sumakobashi sedimentation basin water purification outlet. At the Nakasai Water Filtration Plant, seepage water from the pit and runoff from the sedimentation site during rainfall is turned alkaline to precipitate metals, and after solid-liquid separation, the water is returned to neutral and discharged into the Watarase River. As long as seepage water from the pit continues to flow out, the Nakasai Water Treatment Plant cannot be abolished.

Deposit site

A place where ore scraps (ores with low copper content, ore dressing sludge, and calamites) and other materials are stored, also called a tailings dam. There are 14 tailings disposal sites in Ashio Town, including those that have been publicly announced (the Kotaki site was removed in 1990, and there are now 13 sites). There are also other undisclosed deposition sites that are not governed by the law, as well as accumulation sites for stones dumped in the mines.

The surrounding forests were devastated by mineral poisoning (sulfurous acid gas), logging, wildfires caused by population growth, and logging to secure firewood and coal. Mining operations continue to this day.

Mine

There is one copper mine, Bizen Tateyama, but no other copper was produced in the Ashio area.

Mines

There is one copper mine, called Bizen Tateyama, but no other mines produced copper.

Mine entrance

There are three mine entrances: Motoyamakeng (Arikikeng), Kotakikeng, and Tongdokeng. The Kotakikeng is connected to the main mine in a straight line, and the Tongdokeng tunnel is connected to this thicker tunnel from the side. As a result, the tunnel connecting the three tunnels is T-shaped. The Kotaki-keng was closed in 1954, and the last two tunnels to be used were the Bonsan-keng and the Tongdong-keng. In fact, there was a subtle difference in the location of the Bensankeng and Arikikeng, and there were other main tunnels in close proximity. Usually, these three shafts are collectively referred to as “Motoyakeng. Ariki Keng was initially called Likikeng, but was changed to Ariki for good luck. There is also a tunnel mouth called Sumikoqiao. It is small in size and is considered almost the same as the Tongdongkeng, but it was nominally independent. It existed near the present-day Sumashiqiao Deposit Site.

Ore dressing plant

Located in the Tongdong area. In 1918, a flotation method was introduced to sort the ore into a fine powder using a ball mill, and although the ore was collected by a thickener, the Watarase River became cloudy.

Smelters

The largest smelter was located in the Motoyama area, and there were also smaller smelters in the Kotaki area. Copper was smelted from the ore, and after the 1960s, sulfuric acid was produced by collecting sulfurous acid gas generated during smelting, which was also shipped.

Water Purification Plant

In 1897, the government ordered the water from Ashio’s mining facilities to be precipitated as a measure to prevent mineral poisoning (Second Prevention Order). After the mine closed, water purification facilities continued to operate, with two still in operation as of 2007: the Motoyama Water Purification Plant and the Nakasai Water Purification Plant. There was also a water purification plant in Kotaki, but it was integrated into the Nakasai plant due to its small size. Ashio Copper Mine had five official drainage outlets: the refining plant drainage outlet, the refining karami drainage outlet, the Motoyama water purification drainage outlet, the Nakasai water purification drainage outlet, and the Sumakobashi sedimentation basin water purification outlet. At the Nakasai Water Filtration Plant, seepage water from the pit and runoff from the sedimentation site during rainfall is turned alkaline to precipitate metals, and after solid-liquid separation, the water is returned to neutral and discharged into the Watarase River. As long as seepage water from the pit continues to flow out, the Nakasai Water Treatment Plant cannot be abolished.

Deposit site

A place where ore scraps (ores with low copper content, ore dressing sludge, and calamites) and other materials are stored, also called a tailings dam. There are 14 tailings disposal sites in Ashio Town, including those that have been publicly announced (the Kotaki site was removed in 1990, and there are now 13 sites). There are also other undisclosed deposition sites that are not governed by the law, as well as accumulation sites for stones dumped in the mines.

The surrounding forests were devastated by mineral poisoning (sulfurous acid gas), logging, wildfires caused by population growth, and logging to secure firewood and coal. Mining operations continue to this day.

Mine

There is one copper mine, Bizen Tateyama, but no other copper was produced in the Ashio area.

Mines

There are three mine entrances: Motoyamakeng (Arikikeng), Kotakikeng, and Tongdokeng. The Kotakikeng is connected in a straight line from the Bonsan-keng, while the Tongdokeng is connected to this thicker tunnel from the side. As a result, the tunnel connecting the three tunnels is T-shaped. The Kotaki-keng was closed in 1954, and the last two tunnels to be used were the Bonsan-keng and the Tongdong-keng. In fact, there was a subtle difference in the location of the Bensankeng and Arikikeng, and there were other main tunnels nearby. Usually, these three kens are collectively referred to as the “main mountain kens”. Ariki Keng was initially called Likikeng, but was renamed Ariki for good luck. There is also another tunnel mouth called Sumikoqiao. Although smaller in scale, it is often regarded as almost identical to the Tongdongkeng, but was nominally independent. It existed near the present-day Sumashiqiao Deposit Site.

Ore dressing plant

Located in the Tongdong area. At first, female workers visually identified ores and carried out ore dressing; in 1918, a flotation beneficiation method was introduced by turning ores into a fine powder in a ball mill, and ore was collected with a thickener, but the Watarase River became cloudy.

Smelters

The largest smelter was located in the Motoyama district, and there was a smaller smelter in the Kotaki district. Copper was smelted from the ore, and after the 1960s, sulfurous acid gas generated during smelting was recovered to produce sulfuric acid for shipment.

Water Purification Plant

In 1897, the government ordered the water from Ashio’s mining facilities to be precipitated as a measure to prevent mineral poisoning (Second Prevention Order). Water purification facilities continued to operate after the mine closed, with two still in operation as of 2007: the Motoyama Water Purification Plant and the Nakasai Water Purification Plant. There was also a water purification plant in Kotaki, but it was integrated into the Nakasai plant due to its small size. Ashio Copper Mine had five official drainage outlets: the refining plant drainage outlet, the refining karami drainage outlet, the Motoyama water purification drainage outlet, the Nakasai water purification drainage outlet, and the Sumakobashi sedimentation basin water purification outlet. At the Nakasai Water Filtration Plant, seepage water from the mine during normal times and runoff from the sedimentation site during rainfall is converted to alkaline water, and after precipitation of metals, solid-liquid separation is performed to return the water to neutral before discharge into the Watarase River. As long as the runoff of seepage water from the pit continues, the Nakasai Water Treatment Plant cannot be decommissioned.

Deposit site

A place for storing ore waste (ore with low copper content, beneficiation sludge, calamite), etc., also called a tailings dam. There are 14 publicly announced deposition sites in Ashio (Kotaki deposition site was removed in 1990, and now there are 13 sites). In addition, there are other deposition sites that do not meet legal standards and dumping sites for stones from the mines, such as the Central Ground and the site of former employee housing. Some of these used deposition sites, such as the Arikosawa deposition site, have been revegetated and treated for mining damage, but further management and supplemental planting work is still needed. In addition, the Sumiko Bridge Deposit Site is still used as a discharge point for sludge generated from the Nakasai Water Filtration Plant, discharging the supernatant water after sedimentation.

Employee Housing

Company housing was mainly built near the mine entrance, and most miners walked to work. An elementary school and stores were also built nearby. After the mine closed, the area became uninhabited, and few of these buildings are still standing.

Shrine

The “Motoyama Mine Shrine” is located near the top of the mountain across from the mine. There are two buildings, the main hall and the worship hall, both of which have been abandoned. There is also another shrine at the Tongdokeng pit, with a hall of worship near the sightseeing exit of Ashio Copper Mine.

Cable Cables

In Ashio, cable cars (cableways) were called “teishaku” (iron cables), and in 1890 a line was first built to connect Nikko over the Hosoo Pass. The most extensive line went from Motoyama-ko to Kotaki-ko via Ginzan-daira and then to Neri in Tone-mura. Used to transport goods and ore, several large iron cables were constructed in Ashio Town, but all were removed after the mine closed. There are records that the line was also used to transport mountain climbers, and it appears that it was also used by miners and others for commuting.

Railroad

Railroad tracks were laid on the town’s roads for the transportation of people and goods. The first was a horse-drawn railroad, and later gasoline cars operated along approximately the same route. In many places, the early horse-drawn railroads were later converted to railroads and railroads.