Abstract The reduction in phosphorus content using microwave energy as a heating source has recently received remarkable attention due to the possibility of high heating rates and fracture generation in the particles. Such advantages can lead to a potential increase in productivity in the process of reducing the phosphorus content of iron ore particles, thereby increasing the reuse of large volumes of sterile with a high phosphorus content. Thus, it is highly relevant to understand how the interaction between the phosphate structure and the reaction medium occurs. Thus, this paper deals with the study of a possible kinetic model aiming at the process of reducing the phosphorus content using microwave energy to heat iron ore particles in contact with concentrated sulfuric acid (acid baking). This model treats the microwave oven as a multiphase reactor and two phases are considered simultaneously: liquid and granular or fine solids (crude or comminuted iron ore). First, a basic case consists of the ore/sulfuric acid mixture, in a ratio of 2:1. After heating, the mixture is added to a specific volume of water and then the system is stirred at a speed of 620 rpm. After the leaching process, the liquid was filtered and taken for chemical analysis, which was performed using an ultraviolet spectrometer at a wavelength of 420 nm for phosphorus and 473 nm for iron. Through the scanning electron microscopy (SEM) technique, it was possible to observe the structure of the iron ore particles after their treatment with microwave energy and leaching. Kinetic models of diffusional and chemical control were used to understand the interaction phenomena of sulfuric acid inside the particles. The mixed control kinetic model was also evaluated, in which it was possible to evaluate different parameters regarding the interaction between mineral structure and sulfuric acid as leaching medium. The obtained results indicated that the developed process has relevant utility. The kinetic modeling results contribute to a better understanding of heating phenomena using microwave energy, and also to the development of new cleaner technologies to improve the efficiency of the acid baking/leaching process to reduce particulate phosphorus content in iron ores.

中文翻译：

---

微波能降低铁矿石颗粒磷含量的酸焙工艺扩散系数评价

摘要 使用微波能作为加热源来降低磷含量最近受到了极大的关注，因为它可能会导致颗粒的高加热速率和断裂产生。这些优势可以在降低铁矿石颗粒磷含量的过程中导致生产率的潜在增加，从而增加大量高磷无菌的再利用。因此，了解磷酸盐结构和反应介质之间的相互作用是如何发生的非常重要。因此，本文研究了一种可能的动力学模型，该模型旨在利用微波能加热与浓硫酸接触的铁矿石颗粒（酸焙）来降低磷含量的过程。该模型将微波炉视为多相反应器，同时考虑两相：液体和颗粒或细固体（粗铁矿石或碎铁矿石）。首先，基本情况由比例为 2:1 的矿石/硫酸混合物组成。加热后，将混合物加入特定体积的水中，然后以620rpm的速度搅拌系统。浸出过程后，将液体过滤并进行化学分析，使用紫外光谱仪在波长为 420 nm 的磷和 473 nm 的铁处进行化学分析。通过扫描电子显微镜（SEM）技术，可以观察到铁矿石颗粒经过微波能和浸出处理后的结构。扩散和化学控制的动力学模型被用来理解颗粒内部硫酸的相互作用现象。还评估了混合控制动力学模型，其中可以评估关于矿物结构和作为浸出介质的硫酸之间相互作用的不同参数。所得结果表明所开发的工艺具有相关的实用性。动力学建模结果有助于更好地了解使用微波能的加热现象，也有助于开发新的清洁技术，以提高酸焙/浸出过程的效率，以减少铁矿石中的颗粒磷含量。其中可以评估关于矿物结构和作为浸出介质的硫酸之间相互作用的不同参数。所得结果表明所开发的工艺具有相关的实用性。动力学建模结果有助于更好地了解使用微波能的加热现象，也有助于开发新的清洁技术，以提高酸焙/浸出过程的效率，以减少铁矿石中的颗粒磷含量。其中可以评估关于矿物结构和作为浸出介质的硫酸之间相互作用的不同参数。所得结果表明所开发的工艺具有相关的实用性。动力学建模结果有助于更好地了解使用微波能的加热现象，也有助于开发新的清洁技术，以提高酸焙/浸出过程的效率，以减少铁矿石中的颗粒磷含量。