Double-screw compost turning machine

The double screws turner is the core piece of equipment for achieving "deep-layer turning and comprehensive oxygenation" in aerobic composting and fermentation processes. Powered by counter-rotating twin screws and designed for use with fixed-trough fermentation systems, the machine performs deep-layer mixing, material crushing, oxygenation, and displacement of organic matter within the fermentation trough. It features a significant turning depth, strong oxygen penetration, and uniform fermentation, while ensuring the steady movement of material along the trough.

During aerobic fermentation, the twin-screw turner serves not merely as a mixing tool but as the "operational brain" of the process; through the precise, coordinated movement of its twin screws, it creates an optimal growth environment for aerobic microorganisms. The equipment maintains the compost pile temperature within the ideal fermentation range of 55–70°C—effectively eliminating pathogens and insect eggs—and significantly shortens the fermentation cycle to 15–25 days. Positioned between the initial ingredient mixing stage and the final discharge/post-processing stage, the twin-screw turner acts as the "primary arena" for the aerobic biochemical reaction.

Component Composition and Functional Zoning

From the perspective of the fermentation process, the double screws turner can be categorized into the following functional units:

(I) Turning and agitation unit: Composed of two parallel, symmetrically arranged screw shafts equipped with staggered, wear-resistant turning blades. It is responsible for deeply scooping, breaking up, crushing, mixing, and throwing the material.

(II) Oxygen supply and aeration unit: Achieves natural oxygenation through thorough contact between the material and the air during the twin-screw turning process. Some models are equipped with an aeration system featuring pipes positioned near the screw augers, allowing air to be introduced into the material layer simultaneously during the turning process.

(III) Displacement and conveying unit: Propels the material forward while turning it, driven by the coordinated rotation of the twin screws.

(IV) Depth adjustment unit: Controls the operating depth of the screw shafts via a hydraulic lifting system.

(V) Travel and positioning unit: A travel system that moves along the rails of the fermentation tank.

Production Line Roles and Process Flow

The double screws turner plays a central role in the fermentation stage of an organic fertilizer production line. The complete production process flows as follows: raw material pretreatment (proportioning and mixing) → aerobic fermentation (twin-screw turning) → discharge → crushing → granulation → drying → cooling → screening → packaging.

During the fermentation stage, the twin-screw turner performs several critical tasks: thoroughly mixing and blending the proportioned raw materials and additives; facilitating the exchange of materials between the upper and lower layers of the pile through deep turning; ensuring full contact between the material and air through a throwing action; breaking up compacted material; and gradually advancing the material from the feed end to the discharge end. When used in conjunction with a transfer carriage, a single machine can service multiple fermentation bays. The associated fermentation bays support both continuous and batch discharge operations.