Hydraulic Roller Granulator

Hydraulic Roller Granulator
The hydraulic twin-roll granulator is an upgraded version of the standard twin-roll extrusion granulator; it utilizes dry roll-pressing technology to directly convert dry powder materials into granules. The equipment primarily employs a hydraulic pressurization system to force material through the gap between two counter-rotating rollers, compressing it into sheets or flakes. These are subsequently crushed, granulated, and screened to produce granules that meet specific application requirements. During the roll-pressing process, the material's density increases by 1.5 to 3 times, ensuring the granules achieve the necessary structural strength.
Leveraging a core process that combines hydraulic pressurization with twin-roll extrusion, the machine enables direct granulation of dry powders without the need for binders or wetting agents, thereby significantly simplifying the production workflow. It is widely used in dry and semi-dry granulation applications—such as compound fertilizers, chemical raw materials, and mineral powders—where high granule strength is required. Compared to standard twin-roll granulators, the hydraulic system provides more stable and adjustable extrusion pressure, preventing drops in granulation rates caused by fluctuations in material hardness. Capable of continuous, stable 24-hour operation and adaptable to production needs ranging from small workshops to large-scale industrial facilities, this equipment serves as a core component for dry granulation in the fertilizer, chemical, and mining industries.
Overall Structure and Core Components

The hydraulic twin-roll granulator features a scientifically precise structural design, with a core assembly comprising a hydraulic system, a twin-roll extrusion unit, a screw feeder, a drive system, a PLC control system, and the machine frame. It consists of six major systems:

(I) Hydraulic System: This is the key feature distinguishing this equipment from standard twin-roll granulators; it consists of a hydraulic pump station, hydraulic cylinders, hydraulic piping, and a control valve assembly. The system applies constant pressure (typically adjustable between 10 and 30 MPa) via the cylinders to forcibly compress the material. It features automatic pressure stabilization to compensate for gap pressure in real-time, ensuring consistent and precise molding pressure. Additionally, it includes overload protection: if hard objects are encountered, the system automatically releases pressure and retracts to prevent jamming or equipment damage.

(II) Twin-Roll Extrusion Unit: This is the operational component of the machine, consisting of a pair of counter-rotating pressure rolls. One set of roll bearing housings is fixed within the frame, while the other set floats on frame guide rails, held tightly against the first set by hydraulic cylinder pressure. The rolls are precision-manufactured from high-strength alloy steel, with customizable surface groove patterns to enhance material grip. Matching mold cavities on the roll surfaces allow material to be pressed in under high pressure, forming granules—typically oblate or cylindrical—that mirror the cavity shapes. The gap between the rolls is adjustable, directly influencing granule density and molding quality. To address the tendency of high-hardness materials to slip, the roll surfaces often utilize a "deep arc groove and tooth" design; this generates powerful shear forces, preventing the material from spinning idly against the roll surface.

(III) Screw Feeding System: This includes a metering feeder and a screw pre-compression unit, designed to deliver powdered material evenly into the extrusion zone between the two rolls. Both the metering and feeding units utilize variable-frequency drive (VFD) control for stepless adjustment, ensuring a high level of automation.

(IV) Drive System: Comprising the main motor, gearbox, drive shafts, and gear assembly, this system employs a heavy-duty, dual-output-shaft gearbox and crowned-gear couplings to effectively protect the rolls and main bearings from damage. (V) Electrical Control System: Equipped with a PLC control cabinet, the system allows for precise adjustment of pressure, roll gap, and feed rate. Operators can monitor equipment parameters in real-time via the control panel, and the system can be operated by just one or two people.

(VI) Crushing, Granule Sizing, and Screening System: The formed flake-like material undergoes crushing, sizing, and screening processes to produce uniform, rounded granules; undersized fines are conveyed back to the elevator inlet by a return screw conveyor for recycling into the granulation process.

Applicable Fields and Industry Coverage

Hydraulic double-roller granulators have an extremely wide range of applications.

Fertilizer Industry: Capable of processing raw materials such as potassium sulfate, potassium chloride, urea, ammonium bicarbonate, ammonium chloride, potassium nitrate, monoammonium phosphate (MAP), diammonium phosphate (DAP), ammonium sulfate, and others to produce compound fertilizers, organic fertilizers, and blended fertilizers. Organic Fertilizer Production: Capable of processing decomposed organic materials such as chicken manure, cattle manure, and straw powder.

Chemical Industry: Suitable for granulating a wide variety of powdered materials, including antioxidants, bromochloro-dimethylhydantoin (BCDMH), sodium dichloroisocyanurate, sodium trichloroisocyanurate, cyanuric acid, bleaching powder, zinc oxide, lead oxide, potassium carbonate, strontium carbonate, calcium chloride, sodium metasilicate, sodium orthosilicate, cryolite, aluminum fluoride, brake lining dust, rubber and plastic additives, silica (white carbon black), calcium aluminate, ground calcium carbonate (GCC), single superphosphate (SSP), carnallite, phosphate rock powder, metal powders, fillers, feed additives, pharmaceutical intermediates, steelmaking additives, snow-melting agents, bentonite, alumina powder, phosphogypsum, desulfurization gypsum, mineral processing agents, environmental protection materials, graphite, and carbon black. Mining and Environmental Protection Sectors: Capable of compacting industrial wastes—such as cast iron plant dust, converter dust, and fly ash—into granules, thereby enabling the resource utilization of waste materials.

Types of usable raw materials

The hydraulic double-roller granulator offers exceptional adaptability to raw materials and outstanding versatility.

Fertilizer raw materials: Potassium sulfate, potassium chloride, Russian red potash, compound fertilizers, ammonium chloride, potassium nitrate, monoammonium phosphate (MAP), diammonium phosphate (DAP), ammonium sulfate, and ammonium bicarbonate.

Organic materials: Dried powders of composted livestock and poultry manure (chicken, cattle, sheep, etc.), straw powder, humic acid, etc. Chemical powders: Antioxidants, zinc oxide, metal powders, plant-based fuels, etc.

Industrial waste: Slag, fly ash, desulfurization gypsum, phosphogypsum, etc. The equipment can process powdery materials with a moisture content of 2% to 20%.

Core Strengths and Unique Highlights

The hydraulic double-roller granulator offers the following outstanding advantages:

Binder-free dry granulation: No wetting agents or binders are required, ensuring high product purity. Direct granulation of dry powder eliminates the need for subsequent drying steps, significantly simplifying the production process.

Significant efficiency and energy savings: The streamlined process and direct dry powder granulation reduce energy consumption by 25%–35% compared to traditional granulators. The entire process requires no humidification, thereby eliminating the generation of wastewater and waste gas.

Superior granule quality: Uniform hydraulic pressure results in granules with high strength and density; they are resistant to pulverization and feature smooth, regular surfaces. The granules exhibit a compressive strength of 6–20 N. The resulting granules are uniform in size and highly compact, resisting breakage and caking, which facilitates storage and long-distance transport.

Broad material compatibility: Capable of processing a wide range of materials—including chemical fertilizers, organic fertilizers, chemical powders, and mining dust—allowing for application versatility without the need to replace core components.