What are the different types of asphalt mixing plants?

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Asphalt mix
The Ammann ABC EcoTec Asphalt-Mixing Plant

Asphalt mix plants are used to create hot mix asphalt. It mixes aggregates and bitumen to create the hot mix paving material. The aggregates here can be a single-sized material or it can be a blend of various grades/sizes of materials. The asphalt mixing plant is mainly composed of cold aggregate supply system, drum dryer, coal burner, coal feeder, dust collector, hot aggregate elevator, vibrating screen, filler supply system, weighing and mixing system, asphalt storage, bitumen supply system.

Asphalt  mix plants are generally categorized as batch mixing plants, which produce a series of batches of asphalt and continuous mixing plants (these are generally of the drum mixing type), which produce a continuous flow of asphalt. This categorization reflects not only the mode of production but also highlights different quality control needs. Plants may be used and/or modified to cater to the production of asphalt mixes using recycled asphalt. Several variations of both batch and continuous drum mixing plants have been developed to cater to project needs. There are different types of available asphalt batch mix plants in India covering a wide area of applications, which is discussed below.

Different types asphalt mix plants

Recycled asphalt mix plant

Modern Recycled Asphalt-Mixing Plant provides exceptional technology at a low acquisition price. The plant utilizes multiple coupled geared motors that reduce fuel and minimize maintenance costs. The efficient burner is another cost-saver, while the hourly output capacity makes the plant desirable for any business.

The plant utilizes multiple coupled geared motors that reduce fuel and minimize maintenance costs. The efficient burner is another cost-saver, while the hourly output capacity makes the plant desirable for any business. It provides excellent drying performance with a simple and easy-to-adjust mechanism to set air/fuel ratios for efficient combustion and pollution control. A baghouse is also installed that ensures suspended particulate matter (SPM) levels are within the specified limits. It also provides the utilization of up to 25 percent cold RAP.

The plant can be easily modified to use 25% recycled asphalt, enabling customers to adjust mixes to a specified RAP design. Optional insulation enhances dryer efficiency and reduces fuel consumption. Silo pockets can utilize optional temperature probes. The plant comes with multiple coupled geared motors eliminating the need for a linkage mechanism, thereby limiting parts and maintenance costs. Wear parts are durable and easy to maintain and replace.

Mobile asphalt mix plant

Modern mobile asphalt plants are designed and developed by using the latest international technology and use them for the construction of roads on a small or medium scale. This system is designed and developed for easy assembling and disassembling for convenient moving from one place to another. In this type of plant, the dryer is accurately fabricated to ensure proper heating of aggregates with minimum heat loss. It is supported on steel rollers through steel tyres with idlers and guide rollers and is provided with a segmented driving sprocket.

A fully automatic control panel with feather touch controls is provided for controlling the quantity and quality of production with the operator sitting in air-conditioned comfort. All systems are completely synchronized with automatic/manual control of burners, load cell, mix temperature, cold feet, mineral, bitumen proportions, etc. Manual control is possible through an override system. A single deck vibratory screen is provided to remove over-size aggregate received from the four bin feeder.

Portable asphalt mix plant

The modern product line is designed to fit the needs of today’s producers. Continuous-mix plants come in portable, relocatable and stationary versions. Batch plants, targeted at the export market and certain domestic applications, are engineered to fit a variety of needs. This complete line of plants, and its range of capacities and features. They are available in three sizes, designed for maximum production capacities of 80 or 130 tons per hour (72 or 118 MTPH).

These plants meet the demands of a variety of small, medium and large projects that require quality hot mix asphalt. They offer a compact, highly portable design. Unique for a plant in this class with the ability to run up to 30% With production capacity of 140 tonnes/hr and RAP mixing capability of 50%, the newer models sets the standard for portability, production, and sustainability. The Plant delivers full-size plant features in a compact highly-portable configuration. Each component is designed to maximize mix quality while also maintaining portability and set-up ease.

Stationary asphalt mix plant

Stationary asphalt mixing plant is a complete set of equipment to produce asphalt mixture in bulk. It is well suited to mix asphalt mixture, modified asphalt mixture, and colored asphalt mixture, therefore, it is a piece of requisite equipment for highway building projects, classified highway construction, urban road construction, airport construction and port construction. At present, there are many types of asphalt batching plant stationery on the market.

These batch plants provide the consistency that is crucial to your mix quality. All plant processes and components are carefully developed to ensure that feeding, heating, drying, screening and mixing seamlessly blend together. Helping integrate all the moving parts is the as 1 Control System, which provides leading technology with a user-friendly interface.

Different types asphalt mix plants

Batch asphalt mix plant

In this type of plant, asphalt is produced in batches every 40-50 seconds, depending on the capacity of the plant and the mixing specifications. The newer models with Counter flow technology continuous drum mix plants are setting new standards for asphalt mix production in the 90–120 t/h output classes. The prime benefits of the plant are fuel efficiency, low carbon footprint, environment protection and facility to add RAP.

The heart of this plant is a high efficiency counterflow dryer drum with a matched fully modulating long nose burner. In conventional continuous mixing plants the parallel flow heat transfer technology is used where in the material to be heated and the hot gases flow parallel to each other in the same direction. In a counterflow dryer drum, the material to be heated and the hot gases flow contra to each other meaning in opposite directions. This is a highly efficient heat transfer system to maximize the transfer of heat from hot gases as well as radiation heat from the burner flame to the aggregates. And the spraying of bitumen and filler is done when the hot aggregates pass behind the burner in the same dryer drum.

Asphalt Drum asphalt mix plant

The asphalt drum mix plant process starts with the feeding of cold aggregates into feed bins. It is usually equipped with three or four bin feeders (or more) and aggregates are loaded into different bins as per their sizes. Each bin is provided with separately adjustable gates for controlling the flow of material. There is a long conveyor belt below the bins that takes the aggregates to the scalping screen. Modern models come with a unit following a triple heat transfer system that ensures a total transfer of heat to the aggregates, translating into higher productivity and lower fuel consumption. The heat is transferred to the aggregates using conductive, connective and radiation techniques. The field-proven unique flight design ensures total heat transfer, a thorough mixing & coating, lower emissions and prevention of bitumen oxidation.

The bins of asphalt mixing plants are all-welded and modular in construction, permitting easy addition of bins to meet growing needs. Steep bin walls and valley angels allow free flow of aggregates from the feeders minimizing hold up to materials in the corners and bridging with sticky aggregates. One can opt for a direct heating type or hot oil heated bitumen storage tanks. Storage capacities range from 10 tons to 50 tons. The indirect heating tanks are supplied with a Japanese design thermic oil heater. The Direct heating tanks are supplied with automatically imported pressure jet burners.

Mobile Hot asphalt mix plant

Mobile Hot batch comes at the end of the drying cylinder, with a fuel pump for feeding fuel and air blower for supplying air. Air Blower Driven by the engine through a v-belt and is of suitable capacity for the burners provided. Storage Ring The discharge end of the drying cylinder is provided with a storage ring fitted with lifting buckets that discharge the hot aggregate into the batching chute.

The batching chute has a fixed volume. Hot aggregate is discharged from the chute to the paddle mixer by a lever. A thermometer is supplied to register the temperature of the stones in the chute. A wire rope hoist is provided with a lifting frame for easy and convenient loading of bitumen from barrels into the boiler. The aggregate and bitumen are mixed in a paddle mixer, fitted with two paddle shafts mounted with arms and tips which rotate in opposite directions. The shafts are gear-driven and mounted on lubricated bearings. The paddle tips are replaceable and coated with special hard-facing alloy to give them longer life in operation. This arrangement provides positive mixing and gives a homogenous mix, which is discharged through a door at the bottom operated by a lever.

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