Mineral exploration generates a significant amount of waste, whose improper disposal can cause adverse environmental impacts. This work investigates the use of mining waste processed by gravimetric separation methods, aiming at the production of sustainable construction materials and the elimination of dams, pits, and dry stacks. The waste was subjected to separation processes using a shaking table and a Humphrey spiral, with the objective of separating the clay, sand, and iron contained in the residual material.
Gravimetric methods are based on the difference in density between minerals to promote separation. The shaking table uses vibratory movements combined with a water flow to separate particles according to their density and size. In this process, heavier particles, such as iron, are directed to one end, while lighter particles, such as sand and clay, are collected at the other end. The Humphrey spiral, in turn, uses the centrifugal force generated by the spiral flow to separate particles of different densities, collecting the sand in the outer parts of the spiral and the clay in the intermediate areas.
After separation, the resulting sand was analyzed for its granulometry through sieving. This process involves passing the sand through a series of sieves with different openings, classifying the particles according to their size. Adequate granulometry is crucial to ensure the quality of interlocking blocks, directly influencing their strength and durability.
The processed sand was then used in the production of interlocking paving blocks, employing a vibratory press. This equipment compacts the mixture of sand, cement, and water, forming high-density and high-strength blocks. Interlocking blocks are a sustainable and efficient alternative for paving, offering ease of installation and maintenance, as well as allowing rainwater drainage.
To evaluate the quality of the produced blocks, standard compressive strength tests were carried out. These tests consist of subjecting the blocks to compressive forces until rupture occurs, measuring the maximum strength supported. The interlocking blocks manufactured with the processed waste sand achieved a compressive strength of 14,87 MPa, meeting the normative requirements for paving.
In addition to using sand, the separated clay was used in the manufacture of soil-cement blocks for building construction. The clay was mixed with soil and cement, compacted in specific molds, and cured to achieve adequate strength for civil construction. These soilcement blocks offer advantages in terms of sustainability and cost-benefit, contributing to more ecological constructions.
The iron separated from the waste was pelletized to supply the metallurgical industry. Pelletization involves agglomerating iron fines into pellets, which are then used as raw material in steel production. This process not only adds value to mining waste but also reduces the need for virgin iron ore extraction, promoting sustainability in the metallurgical industry.
The results of this study demonstrate the feasibility of using processed mining waste in the production of sustainable construction materials and supplying the metallurgical industry. The application of gravimetric separation methods proved effective in obtaining materials of adequate quality, and the manufactured products showed satisfactory performance in strength tests. This study reinforces the importance of innovative solutions for mining waste management, promoting material recycling and the circular economy, eliminating the need for dams, pits, and dry stacks.