The spherometer has three straight legs all of the same length that are at the same level and arranged so that their tips form an equilateral triangle. A fourth leg is of adjustable length, and its tip is at the center of the triangle. The spherometer is placed on the lens or mirror surface. Since its outer legs are over an inch (2.5 cm) apart, and all legs must touch the surface, the spherometer cannot be used on very small lenses or mirrors.

Spherometerphysics

Heavy industry, manufacturing, and natural resource-based industries often use large volumes of water and generate wastewaters requiring treatment. Saltworks designs, builds, and operates advanced wastewater treatment plants that economically and reliably treat tough industrial wastewaters.

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Existing removal options for fluoride wastewaters include: 1) calcium fluoride (CaF2) precipitation and coagulation, 2) adsorption, 3) ion-exchange, and 4) membrane-based processes such as reverse osmosis and electrodialysis. An industrial wastewater with a high fluoride concentration is often treated through the CaF2 precipitation and coagulation method. Adsorption, ion-exchange, and reverse osmosis are more often used in drinking water applications and for final fluoride polishing.

The manufacturing of microelectronics generates unique wastewaters. Saltworks can help you to manage wastewater flows from microelectronics production, targeting fluoride, ammonia, metals, and ions, reducing brine waste, and allowing water reuse.

The central leg is adjusted so that all four tips touch the surface at the same time. If the surface is concave (rounded like the bowl of a spoon), the central leg must be longer for the spherometer to fit the surface. On a convex surface (rounded like the back of a spoon), the central leg must be shorter. This central leg is screwed up and down, and a circular disk with a scale marked around its outer edge is fixed to the head of the screw. The disk moves up and down a fixed vertical scale. Both scales are used to measure the difference in height between the fixed legs and the adjustable leg. The vertical scale shows an approximate value of the height difference. Each of its scale divisions corresponds to one complete twist of the screw. The circular scale is marked in fractions of complete screw turns. It gives the additional fraction of a twist (between the vertical scale markings) accurately.

Saltworks Technologies is a leader in the development and delivery of solutions for industrial wastewater treatment and lithium refining. By working with customers to understand their unique challenges and focusing on continuous innovation, Saltworks’ solutions provide best-in-class performance and reliability. From its headquarters in Richmond, BC, Canada, Saltworks’ team designs, builds, and operates full-scale plants, and offers comprehensive onsite and offsite testing services with its fleet of mobile pilots.

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Recent technology and process improvements in chemical precipitation and filtration can address both disadvantages associated with calcium fluoride precipitation and coagulation.

Spherometeris used to measure

Saltworks developed a cost-optimized solution for fluoride removal using our BrineRefine advanced chemical precipitation and XtremeUF ceramic ultrafiltration systems. An example process flow diagram is presented in the figure below. The combination of BrineRefine and XtremeUF in calcium fluoride precipitation and coagulation eliminates the need for large clarification/sedimentation tanks and multimedia filtration and/or cartridge filtration, reducing footprint, maintenance and operating costs.

The spherometer is used to find the radius of curvature of spherical surfaces. Large picture: a convex surface. Insert: a concave surface.

Before the spherometer is used, its zero reading must be checked for accuracy. A flat surface gives a zero height difference and the spherometer is supplied with a piece of flat plate glass on which the instrument can be checked. The vertical scale zero is not at either end of the scale, but somewhere near the middle of it. This is so that both positive and negative height differences, corresponding to convex and concave surfaces, can be measured with the spherometer.

Calcium fluoride precipitation can reduce the fluoride concentration down to about 8–20 mg/L, depending on the total dissolved solids concentration in the wastewater. A second coagulation step, using aluminum-based coagulation agents, is required to further reduce fluoride to less than 5 mg/L.

Spherometerleast count

In the microelectronics industry, fluoride wastewaters are generated during hydrofluoric acid etching of semiconductors. Hydroflouric acid is also employed in the solar cell and metal-plating industries. Typical concentrations of fluoride in these wastewaters can range from 100 mg/L to more than 10,000 mg/L. In general, fluoride discharge limits are less than 20 mg/L if the wastewater can be discharged into a public sewer system, and less than 5 mg/L if the wastewater is discharged into an aquatic environment. In some jurisdictions, the fluoride discharge limit can be less than 2 mg/L. It is noted that some municipalities add fluoride to drinking water (0.5–1.5 mg/L) because of its beneficial prevention of dental cavities. However, excessive fluoride is harmful to human health causing skeletal fluorosis (bone disease).

A spherometer is an instrument used for measuring the radius of curvature of a spherical surface. Spherometers were first used by opticians to measure the curvature of the surface of a lens.

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Solar PVs manufacturing facilities produce industrial wastewater streams with complex chemistries, which must be managed for reuse, discharge, or disposal. Constituents of concern include fluoride, organics, metals, suspended solids, acids, alkalis, and others.

BrineRefine is an improvement to existing chemical precipitation for fluoride removal. BrineRefine uses intelligent controls for automated precise dosing, avoiding lime and calcium chloride under/over-dosing to precipitate CaF2. XtremeUF is an ultra-robust ceramic ultrafiltration system that self-cleans while it operates. XtremeUF filters the CaF2 and Al(OH)3 fine particles from the coagulation process, leaving a clean water filtrate that could be discharged or reused directly in hydrofluoric acid etching of semiconductors. BrineRefine and XtremeUF are fully integrated into a single smart and automated plant.

During CaF2 precipitation, lime is used to neutralize any waste acids in the fluoride wastewaters. With fluoride concentrations less than 1,000 mg/L, lime is often selected as the sole calcium source to precipitate fluoride. Lime has a low solubility at 0.18% by weight so for wastewater with high fluoride concentrations it used together with calcium chloride, which has a high solubility. Excessive lime addition often results in undesired consumption of aluminum coagulants in the downstream coagulation step and increases sludge quantities.

Spherometerexperiment

It isn't the radius of the lens or mirror itself which is of primary importance, but the radius of the sphere to which the curved surface of the lens belongs. This radius is called the radius of curvature, and is the quantity measured by a spherometer.

The calcium fluoride precipitation and coagulation method, however, has two disadvantages: 1) CaF2 from the precipitation step and Al(OH)3 from the coagulation step are both very fine particles, so their sedimentation and clarification times are very long, requiring large footprint clarifiers; and 2) overdosing of lime and coagulation reagents results in a higher chemical cost and a large volume of wet sludge for final dewatering treatment.

Spherometerdiagram

The height difference is directly related to the radius of curvature, which can be calculated from the height difference by a simple formula. A shallow curve gives a small difference in level, and a large radius of curvature. Obviously a shallow lens is a small part of a large sphere. A more sharply curved surface gives a bigger height difference and a smaller radius of curvature.

This article introduces a new type of ceramic membrane system and explains how it opens the application range. An example of treatment of oil and grease in produced water is provided.

Anton von Leeuwenhoek, the Dutch microscopist who specialized in setting and grinding lenses, used a small, almost spherical glass lens in his simple microscope. With this lens he was able to examine the structure of skin, and discover bacteria. One single lens was able to give quite a high magnification because it was small and almost spherical. The image-forming properties of all lenses (and mirrors) depend on the curvature of their surfaces – whether they are sharply curved as in Leeuwenhoek's small spheres or shallower curves which are part of much larger spheres. Lens and mirror surfaces are usually parts of spheres.