A beach placer, also known as a placer deposit, is a type of mineral deposit that forms on the beach or along the shoreline. It is a concentration of valuable or heavy minerals transported and deposited by natural processes such as water currents, waves, and tides. The beach placer is characterized by good mineral separation, concentrated heavy minerals, high roundness of sand grains, few grains, and layers of ore-containing sand grains, and non-mineral sand grain layers are often interlaced into layers. Placer deposits typically consist of minerals, including gold, diamonds, tin, titanium, zircon, and other dense and resistant minerals.
Beach Placers Types
There are many kinds of beach placers, and at least 60 types of beach placers have been discovered worldwide. According to the mineral composition, it can divide into metal placers and non-metal placers.
The proportion of metal placers is relatively large. In metal placer, chromite, magnetite, and titanomagnetite are black, and they are called ferrous metal placers; ilmenite, rutile, zircon, monazite, xenotime, niobite, tantalite, niobium tantalite, etc. have many colors, and are called rare earth metal placers; placer gold, placer platinum, placer tin (also known as cassiterite) are yellow and off-white respectively and are called non-ferrous metal placers.
The proportion of non-metallic placers is small. Diamond, amber sand, garnet, sillimanite, spinel, tourmaline, quartz sand, etc., have different colors and are called non-metallic placers. Among them, diamonds and amber sand are very precious and beautiful.
Common Beach Placers
Placer Gold: These placers contain concentrations of gold particles. Gold placers are often found along riverbanks and in coastal areas where gold-bearing rivers meet the ocean. The action of waves and tides helps to concentrate and deposit the gold particles on the beach.
Placer Diamond: Diamond placers are beach deposits that contain concentrations of diamonds. These placers typically form from the erosion of diamond-bearing rocks and their subsequent transportation by rivers to the coast. Coastal processes further concentrate the diamonds, leading to their deposition on the beach.
Heavy Mineral Placers: Heavy mineral placers comprise various dense and resistant minerals. These minerals may include ilmenite, rutile, zircon, garnet, monazite, etc. Heavy minerals are often concentrated in beach placers due to their specific gravity, allowing them to settle out and accumulate in areas with low wave and current energy.
Placer Tin: Tin placers, also known as cassiterite placers, are deposits containing concentrations of tin minerals. These placers typically form from the weathering and erosion of tin-bearing rocks, with the resulting tin particles being transported to the coast by rivers. The action of waves and tides further concentrates the tin minerals on the beach.
Titanium Placers: Titanium placers consist of concentrations of titanium-bearing minerals, such as ilmenite and rutile. These minerals are resistant to weathering and erosion and are often found in beach placers and other heavy minerals. Titanium placers can have economic importance due to the extraction of titanium for various industrial applications.
Distribution of Beach Placers
Beach placer deposits are widely distributed and can be found almost everywhere in hills, terraces, and sandy coasts, but the mineral types are different in each place.
- Rare earth placers:Primarily found in tropical and subtropical regions, distributed in the Indian Peninsula, Sri Lanka, China, the west coast of Africa at low latitudes, the west coast of the Atlantic Ocean, and the northern Mediterranean coast.
- Placer gold and Placer platinum:More distributed in Alaska, USA.
- Placer tin:Mainly distributed in Malaysia.
- Magnetite:Mostly found in Japan and Canada.
- Titanium magnetite:Mostly concentrated in New Zealand.
- Diamond:Mainly produced on the coast of Southwest Africa and near-shore shallow sea.
- Quartz sand: It is distributed in the broader area and has been discovered in temperate and tropical coastal regions.
There are billions of tons of beach metal placer reserves in the world, among which magnetite, titanomagnetite, and ilmenite are the main ones that exceed 100 million tons; the reserves of zircon, rutile, and monazite are also several million to thousands. More than 10,000 tons; the tin placer reserves in Southeast Asia are also considerable. Among the non-metallic placers, the diamond reserves in Southwest Africa are more than 63 million carats; the world’s quartz sand reserves are at least tens of billions of tons, which can be used continuously for a long time.
Beach Placer Mining
Before choosing the beach placer mining method, we must first understand the geological characteristics of the seaside placer. The formation of coastal placer mines is related to natural forces such as rivers, waves, and tides, so its geological features differ from other mining areas. The ore particles of the seaside placer are fine, the content of organic matter is high, the thickness of the sand layer is unstable, and the composition of the ore is complex, all of which will affect the choice of the mining method of the seaside placer.
Mining Method & Process of Beach Placer
The mining methods of beach placers mainly include open-pit mining and underground mining. Open-pit mining refers to digging ore on the surface, while underground mining refers to mining ore underground. Open-pit mining is mainly adopted for seashore placer mines due to its shallow ore seams. The advantage of open-pit mining is that it can be mined on a large scale, with high efficiency and low cost, but it pollutes the environment more. The advantage of underground mining is that it can reduce environmental pollution, but the price and efficiency are high.
1. Open-pit mining
The open-pit mining process mainly includes exploration, excavation, transportation, and mineral processing.
- Exploration refers to the detailed investigation of the mining area to determine the ore quality and distribution of ore deposits in the mining area.
- Excavation refers to ore excavation in the mining area using excavators, loaders, and other equipment.
- Transportation refers to transporting the mined ore to the beneficiation plant for beneficiation.
- Mineral dressing refers to the mineral processing of transported ore to improve the grade of ore.
2. Underground mining
The underground mining process mainly includes digging, support, mining, transportation, and mineral processing.
- Digging refers to opening up mining tunnels underground.
- Support refers to strengthening the tunnels to prevent landslides.
- Mining refers to mining ore in the tunnels.
- Transportation refers to transporting the mined ore to the ground.
- Mineral dressing refers to the mineral processing of transported ore to improve the grade of ore.
Beach Placer Mineral Processing
The beneficiation methods of beach placers mainly include gravity separation, magnetic separation, flotation, and other methods. Gravity separation refers to the separation by using the density difference of minerals, magnetic separation refers to the separation by using the magnetic difference of minerals, and flotation is the separation by using the difference of hydrophilicity and hydrophobicity of minerals. Due to its complex mineral composition, the beach placer is generally used to combine multiple beneficiation methods for beneficiation. The purpose of beneficiation is to improve the ore’s grade, reduce the ore’s impurities, and increase the economic value of the ore.