Concrete Recycling Process and Iron Remover Selection Technique

The benifits of concrete waste recycling

Aiming at the features of concrete waste, the treatment of concrete waste is mainly based on the crushing process. A crushing line dominated by the concrete crusher is applied to crush and screen of the concrete waste, and the iron remover equipped in the crusher and conveyor to remove the iron materials such as steel.

Concrete waste has several applications

After crushing and screening, the concrete waste is processed into the aggregate (sand and gravel) of a specific size that is applied for road construction, bricks (baking-free brick, permeable brick, etc), cement admixture and other aspects to achieve the recycling of concrete waste.

This article will take the damage of over iron to crusher as the starting point, analyze the three most popular concrete recycling process, and provide you with a variety of skills of concrete crushing iron removal device selection, hope to be helpful to you.

Damage of iron to crusher (taking jaw crusher as an example):

Excessive wear of wearing parts

When iron enters into the cavity, and the size of iron is larger than the discharging port of jaw crusher, the iron will be blocked between the fixed and movable jaw plate, which will make the fixed jaw plate and movable jaw plate collide with each other, resulting in the looseness or cracking of jaw plates.

Damage to the plate of jaw crusher

Change the parameters of jaw crusher

When the iron enters into the crushing cavity of jaw crusher, the jaw crusher can't crush it cause the iron is too hard. When the jaw crusher attempts to crush the iron, the pressure between the jaw plates would be rise immediately, and the power and oil temperature will be rise subsequently.

When jaw crusher detects there is iron entering into the cavity, it will reduce the crushing pressure, lower its main shaft, expand the discharging port to prevent jaw crusher from heavy damage. However, in the whole iron discharging process, the damage to the jaw crusher is very large.

Causing spindle fracture the frame body cracking

When iron enters into the cavity, the uneven force and change of oil pressure caused by impact have an influence on the lower frame and spindle. Meanwhile, the frame and spindle will be worn and cracked because the jaw crusher discharges iron frequently. Therefore, the spindle and frame will be fixed up even replaced by new parts, which will cost a lot.

Jaw crusher's frame

Concrete crushing process and iron remover selection

Concrete crushing process

Process one

Vibrating feeder + iron remover + light material processor + concrete crusher + vibrating screen. Concrete waste is always mixed with metals, glass, wood, and other impurities, so iron remover (magnetic separator) is set in the concrete crushing process to remove the iron.

Process 1: iron remover + concrete crusher

After removing iron and other light impurities by iron remover, concrete waste is sent into the cavity of crusher by vibrating feeder and then crushed into several sizes. Then the crushed concrete is screened by the vibrating screen and divided into three piles in the particle sizes of 0-5 mm, 5-20 mm and 20-40 mm.

Besides, to guarantee the performance of finished concrete products, the light material processor is adopted to separate the scraps of paper, plastic and wood and other light materials. And this process is one of the best concrete crushing lines with the advantages of low investment, simple techniques and great particles of the finished products.

Process two

Vibrating feeder + iron remover + light material processor + PE jaw crusher + PF impact crusher + vibrating screen. Process two consists of two crushers, and PE jaw crusher as the primary crusher and PF impact crusher as the second crusher. Other machines are iron remover, light materials processor, vibrating screen, vibrating feeder, etc.

Process 2: Iron remover + PE jaw crusher + impact crusher

Due to the scrap iron and plastic are hard to separate manually, there are set iron remover and light material separator to improve the fineness of the finished product. Recycling aggregate often contains a lot of impurities such as clay, silt, fine scraps, and they adhere to the surface of aggregate which reduce the strength of recycled concrete. Therefore, after crushing and screening, the recycled concrete should be washed further.

Note:

Although the hardness of concrete is lower, the hammer crusher still can't be the second crusher for its treatment. The reason is that there are some non-crushed materials after processing by iron remover and jaw crusher. The hammer will be damage badly as it contacts the steel, which will influence the normal operation of the hammer crusher.

Process three:

This process adopts the special concrete mobile crushing plant (portable concrete crusher), which differs from the common crushing plant. The concrete mobile crushing plant is equipped with an iron remover designed by the engineers of HXJQ Mining Machinery.

Process 3: iron remover + concrete mobile crushing plant

When the concrete waste enters the mobile crushing plant (portable concrete crusher), it warps the steel by the strong crushing pressure, then the curved steel is separated by the iron remover and delivered into the steel pile.

The concrete waste and construction waste processed by the mobile crushing plant (portable concrete crusher) can be applied widely, and they can be used to make high-grade concrete, sand, bricks, wall plate, and other building materials. After adding the Portland materials, they can be applied for road construction, etc.

The above three concrete recycling process adopt iron remover, which can separate the iron from the concrete waste to guarantee the normal and safe operation of crushers and mills, meanwhile, it can prevent the conveyor from damages and improve the fineness of recycling concrete. Therefore, iron remover is the necessary equipment in the concrete recycling process.

Section of iron remover in concrete crushing process

The iron remover is divided into several types according to the removing methods, such as artificial remove, automatic remove, program-controlled remove, etc. When choosing the suitable iron remover, the iron content in materials, iron removing requirements, using conditions and features of iron remover should be considered.

Selection of iron remover

• When there is too much iron in concrete waste, the self-discharging electromagnetic iron remover or permanent magnetic separators with continuous iron discharge capacity should be adopted.

• When there is some iron contained in the concrete waste, the manual-discharging electromagnetic iron remover or permanent magnetic separators should be considered. And Proper suspension height of iron remover facilitates iron removal.

• When there is less iron in concrete waste, metal detector and self-discharging electromagnetic iron remover can be combined, which is power-saving and energy-saving and has a good iron removing performance.

• When the power supply is limited, it is better to choose permanent magnetic separators.

• When there is too much dust in the working site, it is better to choose the closed iron remover.

• When there are too many impurities that can't be absorbed by iron remover, it is better to choose a metal detector for the inspection.

• When the concrete waste is too thick, or its size is over large, it is better to choose a strong magnetic iron remover.

• When the requirements for the purity of materials is higher, different iron remover can be used jointly. For example, the permanent magnetic separator is set in the front of conveyor, and the belt iron remover is equipped in the middle of the conveyor.

• The permanent magnetic separator is recommended for the conveyor of 1400 mm width, and magnetic iron remover is suitable for the conveyor of over 1400 mm width.