Ultrasonic impedance densitometer is used in the dissolution and evaporation steps to compare with the Na22 densitometer

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In the leaching and evaporation stages of alumina production, the ultrasonic impedance densitometer offers advantages over traditional Na22 (radioactive) densitometers: it not only solves the measurement challenges posed by high temperatures, tendency to form scabs, and the presence of bubbles in such conditions, but also delivers significant improvements in terms of safety and long-term costs. The specific advantages are compared as follows: 1. Safety and compliance: From \"high-risk regulation\" to \"inherent safety\". ① Na22 densitometer: It contains radioactive isotopes (gamma-ray sources), posing a potential risk of leakage and representing a long-term hazard to both personnel and the environment. Companies must obtain a \"Radiation Safety License,\" designate radiation control zones, and conduct regular health checks for employees, equipment inspections, as well as environmental audits. When the equipment is scrapped, high costs are incurred for its proper disposal, resulting in high compliance costs and a heavy management burden. ②Ultrasonic densitometer: It measures using sound waves, is intrinsically safe, and contains no radiation. It belongs to ordinary industrial instruments; no special approvals, protective measures, or dedicated personnel are required, which completely eliminates radiation safety risks and related legal compliance pressures, meeting the ESG (Environment, Social, and Governance) requirements of modern enterprises. 2. Measurement performance: Overcoming the challenges of \"bubbles\" and \"scaling\". The dissolution and evaporation processes (especially in flash tanks) generate large amounts of secondary steam, and the high-temperature slurry tends to form scaling on the surfaces of the equipment, posing a significant challenge to measurement techniques. ①Na22 densitometer: Its measurement principle is based on ray attenuation; the presence of bubbles significantly reduces ray attenuation, causing the instrument to misjudge the density as being lower, which results in severe data distortion (underestimated readings). Scars on the inner walls of the pipeline or measurement chamber can interfere with the path of the rays, affecting the accuracy of measurements, and thus frequent calibration is required. ②Ultrasonic densitometer: Utilizing the principle of acoustic impedance along with intelligent algorithms such as linear frequency modulation analysis, it is able to effectively distinguish the acoustic properties of gases from those of solids/liquids, filter out bubble-related signals, and calculate only the true density of solid-liquid mixtures, thereby ensuring data accuracy in three-phase flow systems involving gas, liquid, and solids. It is not sensitive to minor deposits or scabs on the probe surface; it can automatically compensate for these using algorithms, thereby maintaining measurement stability over longer periods and reducing downtime due to cleaning and maintenance. 3. Maintenance costs and service life: From “continuous investment” to “long-term stability”. Under harsh operating conditions, the stability of the equipment and its maintenance costs are of great importance. ①Na22 densitometer: The half-life of the Na22 radiation source is approximately 2.6 years; over time, its activity decreases naturally, which leads to a reduction in measurement accuracy. It is therefore necessary to replace the radiation source regularly (usually every 1–2 years) or to carry out complex recalibrations, which represents a continuous and costly expense. In the event of a failure, professional agencies are required to carry out maintenance, resulting in long downtime. ②Ultrasonic densitometer: no issues with radiation source degradation, and electronic components have a long lifespan (up to 10 years or more). The probe is made of high-hardness, wear-resistant ceramic, which is resistant to erosion and corrosion; its service life in the dissolution section can typically reach 3-5 years or more. It is essentially maintenance-free in daily use, requiring only occasional inspection of the probe. When installed with online ball valves, it allows for cleaning or replacement without shutting down production or emptying the pipeline, thereby ensuring continuous operation. 4. Real-time response and process optimization: The Na22 densitometer requires a time constant of 1–2 seconds to achieve a stable counting rate; there is a delay in its response, making it difficult to capture instantaneous changes in density. Ultrasonic density meter: With a response time in the millisecond range, it can capture process fluctuations in real time, providing fast and accurate data for key processes such as the formulation of feed materials for dissolution and the control of bottom flow in flash tanks. This facilitates more efficient automated closed-loop control, thereby optimizing steam consumption and reducing alkali usage. 5. In the dissolution and evaporation processes, the ultrasonic PS7000 impedance densitometer, thanks to its safety, precision, durability, and low maintenance requirements, has become an ideal alternative to the Na22 densitometer. It not only addresses various technical challenges but also brings significant safety and economic benefits to enterprises.